FIGURE 10.

Schematic diagram of PTPα-dependent signaling events in proliferating OPCs. In PDGF/bFGF-stimulated OPC proliferation, PTPα activates Fyn to reduce the activities of Ras and Rho, and PTPα acts through unknown mechanisms to inhibit Rac1 and Cdc42 activities. PTPα-Fyn signaling through unknown intermediates up-regulates the expression of p21. The PTPα-Fyn-mediated suppression of Rho activity up-regulates the expression of p27, and this is likely to play a role in promoting cell cycle exit and limiting proliferation.