Suppression of integrin activation: a novel function of a Ras/Raf-initiated MAP kinase pathway

A collection of cDNAs was screened for candidate suppressors of integrin activation by examining their ability to inhibit PAC1 binding to a CHO cell line expressing an active alpha(sub IIb)beta3 chimera. The results confirmed that the small GTP-binding protein, H-Ras, and its effector kinase, RAf-1, are efficient negative regulators of integrin activation. Such suppression was found to be associated with activation of the ERK MAP kinase pathway.