Guanine nucleotide exchange factor (GEF) that modulates the Rho family of GTPases. Promotes the conversion of some member of the Rho family GTPase from the GDP-bound to the GTP-bound form. Isoform 1 exhibits no activity toward RHOA, RAC1 or CDC42. Isoform 2 exhibits decreased GEF activity toward CDC42. Isoform 3 exhibits a weak but significant activity toward RAC1 and CDC42. Isoform 4 exhibits significant activity toward RHOA and CDC42. The truncated DBL oncogene is active toward RHOA, RAC1 and CDC42.
Isoform 1: Membrane
Isoform 3: Membrane. Note: Colocalizes with CDC42 to plasma membrane.