Probably acts as a GEF (guanine nucleotide exchange factor) for the Rho family of small GTP-binding proteins (G proteins) that stimulates the dissociation of GDP to enable subsequent binding of GTP (By similarity). May also chaperone the processing and/or trafficking of small GTPases independently of GEF activity (By similarity). May be involved in the control of polarized cell growth via CDC42-mediated signaling (By similarity). May also be involved in the control of cell-wall organization via RHO1-mediated signaling (By similarity).