ARHGEF28 and ocular melanoma: The rho guanine nucleotide exchange factor 28 (ArhGEF28 or p190RhoGEF or Rgnef), a member of the Dbl family of RhoGEFs which promote the active GTP-bound state of Rho GTPases, was found to be expressed in early- and late-stage OM [75, 76].