Rif is a small (~21 kDa) signaling G protein (more specifically a GTPase), and is a member of the Rho family of GTPases. It is primarily active in the brain and plays a physiological role in the formation of neuronal dendritic spine. This process is regulated by FARP1, a type of activator for RhoA GTPases. Alternatively, Rif can induce the formation of actin stress fibers in epithelial cells. Which is dependent on the activity levels of ROCK proteins since the absence of ROCK activity would mean Rif would be unable to stimulate the growth of stress fibers.
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- Fan, Lifei; Pellegrin, Stephanie; Scott, Alice; Mellor, Harry (April 15, 2010). "The small GTPase Rif is an alternative trigger for the formation of actin stress fibers in epithelial cells" (PDF). Journal of Cell Science. 123 (Pt 8): 1247–1252. doi:10.1242/jcs.061754. PMC 2848113. PMID 20233848.