Claudia Lütticken, Ursula M. Wegenka, Juping Yuan, Jan Buschmann, Chris Schindler, Andrew Ziemiecki, Alisa G. Harpur, Andrew F. Wilks, Kiyoshi Yasukawa, Tetsuya Taga, Tadamitsu Kishimoto, Giovanna Barbieri, Michael Sendtner, Sandra Pellegrini, Peter C. Heinrich, Friedemann Horn

• Interleukin-6, leukemia inhibitory factor, oncostatin M. Interleukin-11, and cilialy neurotrophic factor bind to receptor complexes that share the signal transducer gp130. Upon binding, the ligands rapidly activate DNA binding of acute-phase response factor (APRF), a protein antigenicaly relaled to the p91 subunit of the interferon-stimulated gene factor-(ISGF-3a). These cytokines caused tyrosine phosphorylation of APRF and ISGF-3a p91. Protein kinases of the Jak family were also rapidly tyrosine phosphorylated, and both APRF and Jak1Interleukin-6, leukemia inhibitory factor, oncostatin M. Interleukin-11, and cilialy neurotrophic factor bind to receptor complexes that share the signal transducer gp130. Upon binding, the ligands rapidly activate DNA binding of acute-phase response factor (APRF), a protein antigenicaly relaled to the p91 subunit of the interferon-stimulated gene factor-(ISGF-3a). These cytokines caused tyrosine phosphorylation of APRF and ISGF-3a p91. Protein kinases of the Jak family were also rapidly tyrosine phosphorylated, and both APRF and Jak1 associated with gp130. These data indicate that Jak family protein kinases may participate in IL-6 signaling and that APRF may be activated in a complex with gp130.…