Ras Related C3 Botulinum Toxin Substrate 1 (Rac1)

Rac1 is a GTPase which belongs to the RAS superfamily of small GTP-binding proteins. Members of this superfamily appear to regulate a diverse array of cellular events, including the control of cell growth, cytoskeletal reorganization, and the activation of protein kinases. Two transcript variants encoding different isoforms have been found for this gene. This mutant did bind to POR1 and it induced membrane ruffling and transformation. A second RAC mutant, which bound PAK but not POR1, induced JNK activation but was defective in inducing membrane ruffling and transformation. The authors concluded that the effects of RAC on the JNK cascade and on actin polymerization and cell proliferation are mediated by distinct effector functions that diverge at the level of RAC itself.