POU5F1 and neoplasm: According to early reports of GCTs, stem-cell-related proteins of C-KIT, Oct3/4, transcription factor AP-2 gamma (TFAP2C, or AP-2γ), Nanog, and germ-cell-specific proteins of Melanoma-associated antigen A4 (MAGE-A4), cancer-testis antigen 1B (CTAG1B, or NY-ESO-1), expressed in tumour tissue, and primordial germ cells are regarded as tumour generators to convince “germ cell” theory [75].