POU5F1 and neoplasm: Immunohistochemical staining was commonly used for verification of tumor stem cells in pituitary adenoma; four generic markers, namely Sox2 [11, 19–21], CD133 [22, 23], Nestin [10, 23] and Oct4 [23, 24] were selected and showed immunopositivity in the cultured hPASCs, thus validating the properties of their stemness.