The epithelium that lines the surface of prostate glands contains several cell types, including luminal secretory cells and basal cells of unclear function. Despite the fact that prostate tumors contain cells with a luminal phenotype and lack basal cells, a recent report indicates that the cell of origin for human prostate cancer is a basal cell and not a luminal cell. In contrast, another study indicates the reverse. It is possible that both basal and luminal stem/progenitor cells may independently give rise to prostate cancer; a comparison of the molecular signatures of the target cells of transformation with those of prostate tumors may aid in predicting the phenotypes of tumors with aggressive characteristics.