Cdc42 effector protein 5CDC42 effector protein 5 is a protein that in humans is encoded by the CDC42EP5 gene.FunctionCell division control protein 42, a small Rho GTPase, regulates the formation of F-actin-containing structures through its interaction with the downstream effector proteins. The protein encoded by this gene is a member of the Borg family of CDC42 effector proteins. Borg family proteins contain a CRIB domain. They bind to CDC42 and regulate its function negatively. The encoded protein may inhibit c-Jun N-terminal kinase independently of CDC42 binding. The protein may also play a role in septin organization and inducing pseudopodia formation in fibroblasts .