OCT4 is a member of the POU family of transcription factors, is involved in regulating pluripotency during normal development, and is detectable in embryonic stem and germ cells. OCT4 is a crucial regulator of self-renewal in embryonic stem cells; its expression is potentially correlated with tumorigenesis and can affect tumor recurrence or resistance to therapies. OCT4 is expressed in undifferentiated pluripotent cells, germ cells in the ovary, and testes. OCT4 Ab is useful in the 

identification of primary as well as metastatic germ cell tumors.