PTEN and posterior cortical atrophy: Liu et al. [33] demonstrate that miR-21 induces tumor angiogenesis through targeting PTEN, leading to activate AKT (also known as Protein Kinase B) and extracellular signal-regulating kinase 1/2(ERK1/2) signaling pathways, and thereby enhancing hypoxia-inducible factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF) expression; HIF-1α is a key downstream target of miR-21 in regulating tumor angiogenesis in human PCa cells.