SOX9 and Familial prostate cancer: In spite these consistent doubts about the role of CD133+ cells in prostate cancer as tumor initiating cells, a recent study reported that CD133+ cells isolated from prostate cancer cell lines showed expression of markers of stem cell differentiation (CD44, OCT4, and SOX9), epithelial to mesenchymal differentiation markers, γ-radiation, and chemotherapy drug resistance [520].