FIG. 10.

Proposed model for PDGF receptor and ERK signaling to c-Fos and AP-1-regulated transcription. PDGF (c-sis) triggers a variety of signaling pathways, including those leading to the activation of the ERK cascade (Raf, MEK, and ERK). This results in the phosphorylation of the ternary complex factor (TCF) by ERK and the stimulation of the activity of the c-fos SRE, thus promoting c-fos expression. Subsequently, ERK phosphorylates c-Fos and that stimulates the transactivating activity of c-Fos, thereby promoting the expression of AP-1-regulated genes.