CCND2 and testicular germ cell tumor: Both SE and EC, had high RNA expression of CCND2, NANOG, and POU5F1 and, furthermore, both SE and EC had reduced RNA expression of RB1. The stepwise increase among GCNIS and the undifferentiated types of TGCT in levels of RNA expression of the three genes supports that the genes are driver genes in the pathogenesis of TGCT.