EDN1 and posterior cortical atrophy: PCa cells supply osteoblastic factors (e.g., bone morphogenetic proteins [BMPs], platelet-derived growth factor [PDGF], endothelin-1 [ET1]) and osteolytic factors (e.g., MMPs and vascular endothelial growth factor [VEGF]) to osteoblasts and osteoclasts, respectively, thereby allowing these cells to elaborate bone-derived growth factors (e.g., transforming growth factor-β [TGF-β], Insulin-like growth factors [IGFs]) for cell growth (Casimiro et al. 2009; Morrissey et al. 2010; Ibrahim et al. 2010).