Rac GTPase-activating protein 1 (RACGAP1), also called MgcRACGAP, had been first detected in 1998 from human testis and germ cell tumor extracts and plays an important role in the Rho GTPase activation cycle by regulating Rho GTPase transformation and GTP hydrolysis stimulation5. The gene discussed is RACGAP1; the disease is germ cell tumor.