May act as a GTPase-activating protein for Rab family protein(s). Highly expressed in testes, expression greatly increased at postnatal day 20 and remained high up to day 90. Moderately expressed in kidney and liver, weakly expressed in intestine, lung, ovaries and stomach. Expression of Growth hormone increased the expression in testis but decreased expression in liver and kidney. Weakly expressed in the testis of the embryo and neonate.