Oct-3/4 is a member of the POU homeodomain family of transcription factors, which is expressed by embryonic stem cells and germ cells. A critical amount of Oct-3/4 is required to maintain stem cell self replication. Down regulation of Oct-3/4 levels are associated with loss of pluripotency. Oct-3/4 has been proposed as a useful marker for germ cell tumors which exhibit features of pluripotentiality, including seminoma/dysgerminoma/germinoma and embryonal carcinoma, and establishing a germ cell origin for some metastatic tumors of uncertain primary origin.
Oct-3/4 is recommended for the detection of specific antigens of interest in normal and neoplastic tissues, as an adjunct to conventional histopathology using non-immunologic histochemical stains.