Figure 9.

A schematic representation of CSF-1R signaling to cyclin D2 gene, in which at least three major pathways are involved. CSF-1 binding activates CSF-1R (shown as a dimer) and causes receptor autophosphorylation on tyrosines. The phosphotyrosines recruit cytoplasmic signaling molecules. Among them, CSF-1R engages three parallel pathways, Src (via Y559), Grb2/Sos/Ras/MEK/ERKs (via Y697), and c-myc (via an unknown site[s]), for full induction of D2. The mechanism by which CSF-1R activates PKCδ and the downstream effector for Src and PKCδ remain unknown. The approximate time zones show one-way travel once from the cell surface to the nucleus, and do not reflect any feedback signaling events. PM, plasma membrane; NM, nuclear membrane.