Erythropoietin increases c-myc mRNA by a protein kinase C-dependent pathway

The peptide hormone erythropoietin is a major regulator of red blood cell production. While red blood cell development has been studied intensively, little is known about the intracellular signaling events that follow the binding of erythropoietin to its receptor on the target cell. We report here that erythropoietin-induced activation of the immediate early gene c-myc requires protein kinase C and that the binding of erythropoietin causes rapid phosphorylation of the major protein kinase C substrate, p80. Our results also argue for modulation of activity of a second signal transduction element in addition to protein kinase C.