臺灣博碩士論文加值系統

STAT3為一細胞內轉錄因子，許多報導指出，STAT3能夠誘導一系列關於細胞週期轉換、細胞增生及細胞存活相關基因的表現，例如cyclin D1、p21/Waf1、c-Myc 以及Bcl-xl。因此，我們認為STAT3活化的訊息傳導路徑不僅能提供細胞生長的優勢，或許它也對細胞抗藥性質有所貢獻。我們在本實驗中嘗試探討STAT3的活化與細胞對抗腫瘤藥物之抗藥性的關聯。本實驗主要在兩個細胞模式中進行，一組為NIH3T3及由它衍生帶有持續活化性STAT3的細胞株，另一組則是由表現高量內源性活化之STAT3的肺腺癌細胞－PC14E6/AS2分別轉殖空質體(AS2-TLH-G5)或帶有dominant-negative STAT3之質體(AS2-S3F-C20)的兩細胞株。我們在這兩個系統中測試alkylating agents、antimetabolites、topoisomerase inhibitors、mitosis inhibitors、natural products (chemopreventive agents)等各類型抗癌藥物對STAT3活化狀態不同的細胞間的毒性差異。細胞活性以MTT assay測量，細胞計畫性死亡及細胞週期則藉流式細胞儀判定。我們發現帶有活化性STAT3的癌細胞對cisplatin和paclitaxel較有抗藥性。我們也觀察到在藥物處理的早期(約3小時)，大部份測試的藥物均會提高PC14PE6/AS2細胞中活化性STAT3的量，然後表現出不同程度下降。活化性STAT3 在藥物處理早期的增加或許可提供細胞對壓力的保護反應機制，我們猜測由於藥物處理早期所引起的氧化壓力導致活化性STAT3的增加，隨著藥物毒性引起細胞計畫性死亡相關因子的釋放使得活化性STAT3出現不同程度下降。此外，在24小時時間點的活化性STAT3表現量與化療藥物的細胞毒性呈現相關性，而化療預防劑則否。為了進一步證實活化性STAT3與抗藥性的關係，我們以JAK2的抑制劑AG490和綠茶萃取物EGCG抑制活化性STAT3表現。以AG490與EGCG作前處理會增加帶有活化性STAT3之癌細胞對cisplatin和paclitaxel的敏感性，卻有利於不具活化性 STAT3細胞在兩種藥物處理下的生存。因此，利用JAK2或STAT3的抑制劑治療癌症須謹慎。利用cDNA微矩陣分析進一步了解活化性STAT3引起抗藥性的相關機制。結果顯示Bfl-1及IAP family (如IAP-1及Survivin)的基因表現在AS2-TLH-G5較高，而Bcl-2、Bcl-x和Mcl-1則否。我們猜測STAT3提供的抗細胞計劃死亡可能非遵循傳統觀點。JAK/STAT pathway、細胞増生、細胞週期、細胞計劃性死亡及抗藥性等方面之相關基因也已分析。綜合以上實驗結果，我們推論以活化性STAT3為標的是改進癌症治療之可行方針。

Activation of STAT3 has been shown to induce expression of a group of genes regulating cell cycle progression, cellular proliferation and survival, such as cyclin D1, p21/Waf1, c-Myc and Bcl-xl. Therefore, STAT3 activation may not only provide a growth advantage to tumor cells but also resistance to chemotherapeutic drugs. We tried to find out the relationship between the activation of STAT3 and anti-cancer agents. We have established a NIH-3T3 cell line (NIH3T3-S3C) that expressed constitutively activated STAT3. Besides, a human lung adenocarcinoma cell line — PC14PE6/AS2 with constitutively activated STAT3- was transfected with dominant-negative STAT3 (AS2-S3F-C20). With these two systems, various categories of anti-cancer agents including alkylating agents, antimetabolites, topoisomerase inhibitors, mitosis inhibitors, natural products (chemopreventive agents), and other categories have been added to cells for evaluating cytotoxic effects. Cell viability was measured by the MTT assay, the degree of cellular apoptosis and progression of cell cycle were analyzed by flow cytometry. We found cells with activated STAT3 were more resistant to cytotoxic agent — cisplatin and paclitaxel — but not others. After treatment with most of anti-cancer agents, the activation of STAT3 in PC14PE6/AS2 cells was further enhanced at earlier period (around 3 hours), and then declined gradually to different levels. The early response after exposure to drugs suggests activation of STAT3 may provide a protective mechanism for cells to stress. We suspect that oxidative stress due to the drug treatment might up-regulate STAT3 activation at earlier period, and the degradation of STAT3 activation at later period may be caused by caspases or other factors generated during drug-induced apoptosis. In addition, the level of STAT3 activation at 24 hours correlated well with cytotoxic activity of chemotherapeutic drugs, but not chemopreventive agents. To confirm the relationship between STAT3 phosphorylation and drug resistance, AG490 — a JAK2 inhibitor and EGCG — a component of green tea extracts were used to inhibit activation of STAT3. The pretreatment of AG490 or EGCG sensitize cancer cells with activated STAT3 to cisplatin and paclitaxel, but induce opposite effect in cells in which activation of STAT3 was blocked. Therefore treating cancer with inhibitors of JAK2 or STAT3 should be careful. To uncover more underlying mechanisms for the drug resistance induced by activated STAT3, cDNA microarray studies were performed. A preliminary analysis found Bfl-1, instead of Bcl-2, Bcl-x or Mcl-1, has the highest expression in AS2-TLH-G5 cells, and several IAP family genes (eg. IAP-1 and Survivin) are also up-regulated in the cells, suggesting the anti-apoptotic signals from STAT3 in AS2 cells may not follow the conventional concepts. The expressions of genes about JAK/STAT pathway, cellular proliferation, cell cycle progression, apoptosis and drug resistance have also been analyzed. These results from the current study provide valuable information for targeting activated STAT3 in the treatment of neoplastic diseases.

Index
Abstract in Chinese… … … … … … … … … … … … I
Abstract in English… … … … … … … … … … … … III
Acknowledgements.… … … … … … … … … … … … … V
Index… … … … … … … … … … … … … … … … … VI
List of Tables… … … … … … … … … … … … … … VIII
List of Figures… … … … … … … … … … … … … … IX
1. Introduction
1.1 The STATs family… … … … … … … … … … … … … … … … … … … .1
1.2 The mechanism of JAK-STAT pathway… … … … … … … … … … ...1
1.3 The negative regulation of JAK-STAT pathway… … … … … … … ..3
1.4 The physiological functions of STAT3… … … … … … … … … … … .5
1.5 STAT3 and tumorigenesis… … … … … … … … … … … … … … … … .6
2. Materials and Methods
2.1 Cell line and culture… … … … … … … … … … … … … … … … … … ..9
2.2 Anti-cancer agents… … … … … … … … … … … … … … … … … … ..10
2.3 Cytotoxic assay─MTT method… … … … … … … … … … … … … .10
2.4 Western blot analysis… … … … … … … … … … … … … … … … … ..11
2.5 Cell cycle analysis… … … … … … … … … … … … … … … … … … ..12
2.6 Apoptosis analysis… … … … … … … … … … … … … … … … … … ..12
2.7 Isolation of total RNA─TRIzol method… … … … … … … … … … 13
3. Results
3.1 Cells with constitutively activated STAT3 are more resistant to
cisplatin and paclitaxel… … … … … … … … … … … … … … … … … 14
3.2 The effects of cisplatin and paclitaxel on apoptosis and the progression of cell cycle
apoptosis… … … … … … … … … … … … … … … … … … .16
3.3 Influence of anti-cancer agent on activation of STAT3 and its
correlation with cytotoxic effect of that particular drug… … … … .17
3.4 AG490, a JAK2 inhibitor, can modulate cellular response to
cisplatin and paclitaxel… … … … … … … … … … … … … … … … … 18
3.5 The effects of combined treatment of cisplatin and paclitaxel with
chemoprevention agent EGCG… … … … … … … … … … … … … ...19
3.6 Expression of Bcl-2 and Bcl-xl in the STAT3-activated and
STAT3-inactivated cancer cell lines… … … … … … … … … … … … 20
3.7 cDNA microarray studies reveal differentially expressed genes in
AS2 cells with or without constitutively activated STAT3...… … ..20
4. Discussion… … … … … … … … … … … … … … … … … … … … … … 23
5. References… … … … … … … … … … … … … … … … … … … … … … 28

Abu-Qare AW, Elmasry E, Abou-Donia MB. A role for P-glycoprotein in environmental toxicology. J. Toxicol. Environ. Health. B. Crit. Rev. 6: 279-288, 2003.
Akira S. Roles of STAT3 defined by tissue-specific gene targeting. Oncogene 19: 2607-2611, 2000.
Becker S, Groner B, Muller CW. Three-dimensional structure of the Stat3beta homodimer bound to DNA. Nature 394: 145-151, 1998.
Bienvenu F, Gascan H, Coqueret O. Cyclin D1 represses Stat3 activation through a Cdk4-independent mechanism. J. Biol. Chem. 276: 16840-16847, 2001.
Bowman T, Broome MA, Sinibaldi D, Wharton W, Pledger WJ, Sedivy JM, Irby R, Yeatman T, Courtneidge SA, Jove R. Stat3-mediated Myc expression is required for Src transformation and PDGF-induced mitogenesis. Proc. Natl. Acad. Sci. USA. 98: 7319-7324, 2001.
Bowman T, Garcia R, Turkson J, Jove R. STATs in oncogenesis.
Oncogene 19: 2474-2488, 2000.
Bromberg JF. Stat proteins and oncogenesis. J. Clin. Invest. 109: 1139-1142, 2002.
Bromberg JF, Horvath CM, Besser D, Lathem WW, Darnell JE Jr. Stat3 activation is required for cellular transformation by v-src. Mol. Cellu. Biol. 18: 2553-2558, 1998.
Bromberg JF, Wrzeszczynska MH, Devgan G, Zhao Y, Pestell RG, Albanese C, Darnell JE Jr. Stat3 as an oncogene. Cell 98: 295-303, 1999. Erratum in: Cell 99: 239, 1999.
Carballo M, Conde M, Bekay RE, Martin-Nieto J, Camacho MJ, Monteseirin J, Conde J, Bedoya FJ, Sobrino F. Oxidative stress triggers STAT3 tyrosine phosphorylation and nuclear translocation in human lymphocytes. J. Biol. Chem. 274: 17580-17586, 1999.
Chapman RS, Lourenco PC, Tonner E, Flint DJ, Selbert S, Takeda K, Akira S, Clarke AR, Watson CJ. Suppression of epithelial apoptosis and delayed mammary gland involution in mice with a conditional knockout of Stat3. Genes Dev. 13: 2604-2616, 1999.
Chen X, Vinkemeier U, Zhao Y, Jeruzalmi D, Darnell JE Jr, Kuriyan J. Crystal structure of a tyrosine phosphorylated STAT-1 dimer bound to DNA. Cell 93: 827-839, 1998.
Chung CD, Liao J, Liu B, Rao X, Jay P, Berta P, Shuai K. Specific inhibition of Stat3 signal transduction by PIAS3. Science 278: 1803-1805, 1997.
Costa-Pereira AP, Tininini S, Strobl B, Alonzi T, Schlaak JF, Is''harc H, Gesualdo I, Newman SJ, Kerr IM, Poli V. Mutational switch of an IL-6 response to an interferon-gamma-like response. Proc. Natl. Acad. Sci. USA. 99: 8043-8047, 2002.
Darnell JE Jr. Phosphotyrosine signaling and the single cell:metazoan boundary. Proc. Natl. Acad. Sci. USA. 94: 11767-11769, 1997.
Darnell JE Jr. STATs and gene regulation. Science 277: 1630-1635, 1997.
David M, Chen HE, Goelz S, Larner AC, Neel BG. Differential regulation of the alpha/beta interferon-stimulated Jak/Stat pathway by the SH2 domain-containing tyrosine phosphatase SHPTP1. Mol. Cell Biol. 15: 7050-7058, 1995.
Decker T, Kovarik P. Serine phosphorylation of STATs. Oncogene 19: 2628-2637, 2000.
Decker T, Lew DJ, Mirkovitch J, Darnell JE Jr. Cytoplasmic activation of GAF, an IFN-gamma-regulated DNA-binding factor. EMBO J. 10:927-932, 1991.
Ehret GB, Reichenbach P, Schindler U, Horvath CM, Fritz S, Nabholz M, Bucher P. DNA binding specificity of different STAT proteins. Comparison of in vitro specificity with natural target sites. J. Biol. Chem. 276: 6675-6688, 2001.
Endo TA, Masuhara M, Yokouchi M, Suzuki R, Sakamoto H, Mitsui K, Matsumoto A, Tanimura S, Ohtsubo M, Misawa H, Miyazaki T, Leonor N, Taniguchi T, Fujita T, Kanakura Y, Komiya S, Yoshimura A. A new protein containing an SH2 domain that inhibits JAK kinases. Nature 387: 921-924, 1997.
Epling-Burnette PK, Zhong B, Bai F, Jiang K, Bailey RD, Garcia R, Jove R, Djeu JY, Loughran TP Jr, Wei S. Cooperative regulation of Mcl-1 by Janus kinase/stat and phosphatidylinositol 3-kinase contribute to granulocyte-macrophage colony-stimulating factor-delayed apoptosis in human neutrophils. J. Immunol. 166: 7486-7495, 2001.
Fernandes A, Hamburger AW, Gerwin BI. ErbB-2 kinase is required for constitutive stat 3 activation in malignant human lung epithelial cells. Int. J. Cancer 83: 564-570, 1999.
Finkel T. Oxidant signals and oxidative stress. Curr. Opin. Cell Biol. 15(2): 247-254, 2003.
Fu XY, Schindler C, Improta T, Aebersold R, Darnell JE Jr. The proteins of ISGF-3, the interferon alpha-induced transcriptional activator, define a gene family involved in signal transduction. Proc. Natl. Acad. Sci. USA, 89: 7840-7843, 1992.
Fukada T, Ohtani T, Yoshida Y, shirogane T, Nishida K, Nakajima K, Hibi M, Hirano T. STAT3 orchestrates contradictory signals in cytokine-induced G1 to S cell-cycle transition. EMBO J. 17: 6670-6677, 1998.
Gale GR, Rosenblum MG, Atkins LM, Walker EM Jr, Smith AB, Meischen SJ. Antitumor action of cis-dichlorobis (methylamine) platinum(II). J. Natl. Cancer Inst. 51: 1227-1234, 1973.
Hirano T, Ishihara K, Hibi M. Roles of STAT3 in mediating the cell growth, differentiation and survival signals relayed through the IL-6 family of cytokine receptors. Oncogene 19, 2548-2556, 2000.
Hong F, Jaruga B, Kim WH, Radaeva S, El-Assal ON, Tian Z, Nguyen VA, Gao B. Opposing roles of STAT1 and STAT3 in T cell-mediated hepatitis: regulation by SOCS. J. Clin. Invest. 110: 1503-1513, 2002.
Hou XS, Melnick MB, Perrimon N. Marelle acts downstream of the Drosophila HOP/JAK kinase and encodes a protein similar to the mammalian STATs. Cell 84: 411-419, 1996. Erratum in: Cell 85: following 290, 1996.
Irie-Sasaki J, Sasaki T, Matsumoto W, Opavsky A, Cheng M, Welstead G, Griffiths E, Krawczyk C, Richardson CD, Aitken K, Iscove N, Koretzky G, Johnson P, Liu P, Rothstein DM, Penninger JM. CD45 is a JAK phosphatase and negatively regulates cytokine receptor signalling. Nature 409: 349-354, 2001.
Kaptein A, Paillard V, Saunders M. Dominant negative stat3 mutant inhibits interleukin-6-induced Jak-STAT signal transduction. J. Biol. Chem. 271: 5961-5964, 1996.
Klingmuller U, Lorenz U, Cantley LC, Neel BG, Lodish HF. Specific recruitment of SH-PTP1 to the erythropoietin receptor causes inactivation of JAK2 and termination of proliferative signals. Cell 80: 729-738, 1995.
Krebs DL, Hilton DJ. SOCS proteins: negative regulators of cytokine signaling. Stem Cells 19: 378-387, 2001.
Lee CK, Bluyssen HA, Levy DE. Regulation of interferon-alpha responsiveness by the duration of Janus kinase activity. J. Biol. Chem. 272: 21872-21877, 1997.
Levitzki A. Tyrphostins: tyrosine kinase blockers as novel antiproliferative agents and dissectors of signal transduction. FASEB J. 6: 3275-3282, 1992.
Levy DE, Darnell JE Jr. Stats: transcriptional control and biological impact. Nat. Rev. Mol. Cell Biol. 3: 651-662, 2002.
Liao J, Fu Y, Shuai K. Distinct roles of the NH2- and COOH-terminal domains of the protein inhibitor of activated signal transducer and activator of transcription (STAT) 1 (PIAS1) in cytokine-induced PIAS1-Stat1 interaction. Proc. Natl. Acad. Sci. USA. 97: 5267-5272, 2000.
Masuda M, Suzui M, Weinstein IB. Effects of epigallocatechin-3-gallate on growth, epidermal growth factor receptor signaling pathways, gene expression, and chemosensitivity in human head and neck squamous cell carcinoma cell lines. Clin. Cancer Res. 7: 4220-4229, 2001.
Meydan N, Grunberger T, Dadi H, Shahar M, Arpaia E, Lapidot Z, Leeder JS, Freedman M, Cohen A, Gazit A, Levitzki A, Roifman CM. Inhibition of acute lymphoblastic leukaemia by a Jak-2 inhibitor. Nature 379: 645-648, 1996.
Naka T, Narazaki M, Hirata M, Matsumoto T, Minamoto S, Aono A, Nishimoto N, Kajita T, Taga T, Yoshizaki K, Akira S, Kishimoto T. Structure and function of a new STAT-induced STAT inhibitor. Nature 387: 924-929, 1997.
Negoro S, Kunisada K, Fujio Y, Funamoto M, Darville MI, Eizirik DL, Osugi T, Izumi M, Oshima Y, Nakaoka Y, Hirota H, Kishimoto T, Yamauchi-Takihara K. Activation of signal transducer and activator of transcription 3 protects cardiomyocytes from hypoxia/reoxygenation- induced oxidative stress through the upregulation of manganese superoxide dismutase. Circulation 104: 979-981, 2001.
Ni Z, Lou W, Leman ES, Gao AC. Inhibition of constitutively activated Stat3 signaling pathway suppresses growth of prostate cancer cells. Cancer Res. 60: 1225-1228, 2000.
Nicholson SE, De Souza D, Fabri LJ, Corbin J, Willson TA, Zhang JG, Silva A, Asimakis M, Farley A, Nash AD, Metcalf D, Hilton DJ, Nicola NA, Baca M. Suppressor of cytokine signaling-3 preferentially binds to the SHP-2-binding site on the shared cytokine receptor subunit gp130. Proc. Natl. Acad. Sci. USA. 97: 6493-6498, 2000.
Ohtani T, Ishihara K, Atsumi T, Nishida K, Kaneko Y, Miyata T, Itoh S, Narimatsu M, Maeda H, Fukada T, Itoh M, Okano H, Hibi M, Hirano T. Dissection of signaling cascades through gp130 in vivo: reciprocal roles for STAT3- and SHP2-mediated signals in immune responses. Immunity 12: 95-105, 2000.
Real PJ, Sierra A, De Juan A, Segovia JC, Lopez-Vega JM, Fernandez-Luna JL. Resistance to chemotherapy via Stat3-dependent overexpression of Bcl-2 in metastatic breast cancer cells. Oncogene 21: 7611-7618, 2002.
Ruvolo PP, Deng X, May WS. Phosphorylation of Bcl2 and regulation of apoptosis. Leukemia 15: 515-522, 2001.
Saito S, Frank GD, Mifune M, Ohba M, Utsunomiya H, Motley ED, Inagami T, Eguchi S. Ligand-independent trans-activation of the platelet-derived growth factor receptor by reactive oxygen species required protein kinase c-delta and c-Src. J. Biol. Chem. 277: 44695-44700, 2002.
Sano S, Itami S, Takeda K, Tarutani M, Yamaguchi Y, Miura H, Yoshikawa K, Akira S, Takeda J. Keratinocyte-specific ablation of Stat3 exhibits impaired skin remodeling, but does not affect skin morphogenesis. EMBO J. 18: 4657-4668, 1999.
Schiff PB, Fant J, Horwitz SB. Promotion of microtubule assembly in vitro by taxol. Nature 277: 665-667, 1979.
Schindler C, Fu XY, Improta T, Aebersold R, Darnell JE Jr. Proteins of transcription factor ISGF-3: one gene encodes the 91-and 84-kDa ISGF-3 proteins that are activated by interferon alpha. Proc. Natl. Acad. Sci. USA, 89: 7836-7839, 1992.
Schmitz J, Weissenbach M, Haan S, Heinrich PC, Schaper F. SOCS3 exerts its inhibitory function on interleukin-6 signal transduction through the SHP2 recruitment site of gp130. J. Biol. Chem. 275: 12848-12856, 2000.
Shah MA, Schwartz GK. Cell cycle-mediated drug resistance: an emerging concept in cancer therapy. Clin. Cancer Res. 7: 2168-2181, 2001.
Shen Y, Devgan G, Darnell JE Jr, Bromberg JF. Constitutively activated Stat3 protects fibroblasts from serum withdrawal and UV-induced apoptosis and antagonizes the proapoptotic effects of activated Stat1. Proc. Natl. Acad. Sci. USA. 98: 1543-1548, 2001.
Shibata R, Kai H, Seki Y, Kato S, Wada Y, Hanakawa Y, Hashimoto K, Yoshimura A, Imaizumi T. Inhibition of STAT3 prevents neointima formation by inhibiting proliferation and promoting apoptosis of neointimal smooth muscle cells. Hum. Gene Ther. 14: 601-610, 2003.
Simon AR, Rai U, Fanburg BL, Cochran BH. Activation of the JAK-STAT pathway by reactive oxygen species. Am. J. Physiol. 275:C1640-1652, 1998.
Song JI, Grandis JR. STAT signaling in head and neck cancer. Oncogene 19: 2489-2495, 2000.
Takeda K, Clausen BE, Kaisho T, Tsujimura T, Terada N, Forster I, Akira S. Enhanced Th1 activity and development of chronic enterocolitis in mice devoid of Stat3 in macrophages and neutrophils. Immunity 10: 39-49, 1999.
Takeda K, Noguchi K, Shi W, Tanaka T, Matsumoto M, Yoshida N, Kishimoto T, Akira S. Targeted disruption of the mouse Stat3 gene leads to early embryonic lethality. Proc. Natl. Acad. Sci. USA. 94: 3801-3804, 1997.
Turkson J, Bowman T, Garcia R, Caldenhoven E, De-Groot RP, Jove R. Stat3 activation by Src induces specific gene regulation and is required for cell transformation. Mol. Cellu. Biol. 18: 2545-2552, 1998.
Turkson J, Jove R. STAT proteins: novel molecular targets for cancer drug discovery. Oncogene 19: 6613-6626, 2000.
Vinkemeier U, Cohen SL, Moarefi I, Chait BT, Kuriyan J, Darnell JE Jr. DNA binding of in vitro activated Stat1 alpha, Stat1 beta and truncated Stat1: interaction between NH2-terminal domains stabilizes binding of two dimers to tandem DNA sites. EMBO J. 15: 5616-5626, 1996.
Vinkemeier U, Cohen SL, Moarefi I, Chait BT, Kuriyan J, Darnell JE Jr. DNA binding of in vitro activated Stat1 alpha, Stat1 beta and truncated Stat1: interaction between NH2-terminal domains stabilizes binding of two dimers to tandem DNA sites. EMBO J. 15: 5616-5626, 1996.
Wierenga AT, Schuringa JJ, Eggen BJ, Kruijer W, Vellenga E. Downregulation of IL-6-induced STAT3 tyrosine phosphorylation by TGF-beta1 is mediated by caspase-dependent and -independent processes. Leukemia 16: 675-682, 2002.
Xu X, Sun YL, Hoey T. Cooperative DNA binding and sequence-selective recognition conferred by the STAT amino-terminal domain. Science 273: 794-797, 1996.
Yan R, Small S, Desplan C, Dearolf CR, Darnell JE Jr. Identification of a Stat gene that functions in Drosophila development. Cell 84: 421-430, 1996.
Yano S, Shinohara H, Herbst RS, Kuniyasu H, Bucana CD, Ellis LM, Davis DW, McConkey DJ, Fidler IJ. Expression of vascular endothelial growth factor is necessary but not sufficient for production and growth of brain metastasis. Cancer Res. 60: 4959-4967, 2000.
Yasukawa H, Misawa H, Sakamoto H, Masuhara M, Sasaki A, Wakioka T, Ohtsuka S, Imaizumi T, Matsuda T, Ihle JN, Yoshimura A. The JAK-binding protein JAB inhibits Janus tyrosine kinase activity through binding in the activation loop. EMBO J. 18: 1309-1320, 1999.
Yoshimura A, Ohkubo T, Kiguchi T, Jenkins NA, Gilbert DJ, Copeland NG, Hara T, Miyajima A. A novel cytokine-inducible gene CIS encodes an SH2-containing protein that binds to tyrosine-phosphorylated interleukin 3 and erythropoietin receptors. EMBO J. 14: 2816-2826, 1995.
Zhong Z, Wen Z, Darnell JE Jr. Stat3: a STAT family member activated by tyrosine phosphorylation in response to epidermal growth factor and interleukin-6. Science 264: 95-98, 1994.