POU5F1 and prostate cancer: In the current study, in order to determine whether certain stem cell markers may be used for the diagnosis of prostate cancer, the immunohistochemical expression of NANOG, OCT4, CD133 and NESTIN, which are well-known stem cell markers, were investigated in 38 cases from a total of 114 biopsy specimens obtained from Japanese patients with prostate cancer between January 2011 and December 2011.