One of the best examples to illustrate both cellular and lineage plasticity is the AR+ prostate cancer (PCa) treated with antiandrogens, where castration-resistant PCa (CRPC) may manifest as AR− adenocarcinoma (i.e., CRPC-adeno), which maintains the epithelial lineage, or as AR− neuroendocrine (NE) type of CRPC (i.e., CRPC-NE), which has switched lineage from epithelial to NE. This evidence concerns the gene AR and prostate cancer.