Furthermore, several groups have reported that Oct-4 is expressed in human tumours, including testicular germ cell tumours and breast carcinomas, and has a part in human cancer development (Jin et al, 1999; Monk and Holding, 2001; Gidekel et al, 2003; Looijenga et al, 2003). The gene discussed is POU5F1; the disease is childhood testicular germ cell tumor.