Required for the regulation of both a MAP kinase signaling pathway and a cAMP signaling pathway. The activation of these pathways contributes to the pathogenicity of the cells through the induction of the morphological transition from the yeast to the polarized filamentous form. GTP + H2O = GDP + H(+) + phosphate Alternates between an inactive form bound to GDP and an active form bound to GTP. Activated by a guanine nucleotide-exchange factor (GEF) and inactivated by a GTPase-activating protein (GAP). Belongs to the small GTPase superfamily. Ras family.