ACTIVATION OF MITOGEN-ACTIVATED PROTEIN-KINASE CASCADE THROUGH ERYTHROPOIETIN RECEPTOR

Erythropoietin is a cytokine which specifically regulates differentiat ion and proliferation of erythroid progenitor cells. We show here that binding of erythropoietin to its receptor induced activation of prote in tyrosine kinases including Jak2, and of Ras, Raf-1, mitogen-activat ed protein (MAP) kinase kinase and MAP kinases (ERK1 and ERK2). Taken together with other observations, erythropoietin receptor-mediated sig nal activates MAP kinase cascade, which is the common signaling pathwa y activated by other cytokines and growth factor receptors with tyrosi ne kinase activity. (C) 1994 Academic Press, Inc.