ITGA6 and Familial prostate cancer: Remarkably, several of these TF-Ag expressing glycoproteins namely CD44, α2β1 integrin, CD133, CD49f (α6 integrin), and ephrin type-A receptor 2 (EphA2) either serve as most commonly used cell surface prostate cancer stem cell markers (CD44, α2β1 integrin, CD133, CD49f) or control stem cell like functions including clonogenic potential, self-renewal, prostasphere formation, tumor onset, and dissemination of prostate carcinoma to the skeleton (EphA2) [18–27].