May be involved in cell polarity control during the actin-dependent tip growth of pollen tubes. May regulate callose synthase 1 (CALS1) activity through the interaction with UGT1. Inactive GDP-bound Rho GTPases reside in the cytosol, are found in a complex with Rho GDP-dissociation inhibitors (Rho GDIs), and are released from the GDI protein in order to translocate to membranes upon activation. GTP + H2O = GDP + H(+) + phosphate Part of a complex containing ROPGEF1 and PRK2 (PubMed:23024212). Interacts with UGT1, ICR1, ICR2, ICR3, ICR4 and ICR5. Interacts with PHIP1 when activated by GTP (PubMed:18621982). Associated with the membrane when activated. Exclusively expressed in mature pollen and pollen tubes. Belongs to the small GTPase superfamily. Rho family.