Strong heterogeneous staining for human K5 (Figure 2C), a marker of putative prostate epithelial SC/progenitor cells (Sawicki and Rothman 2002; Schalken and van Leenders 2003; van Leenders and Schalken 2001), supports a CSC-like nature and pluripotent cell of origination for these cancers. The gene discussed is KRT5; the disease is cancer.