PSAP and posterior cortical atrophy: Collectively, PSAP and its derivative Sap C play pivotal roles in PCa initiation, progression, and transition to CRPC by engaging in positive feedback regulation of the AR signaling pathway (including upregulating AR expression, promoting its nuclear translocation and phosphorylation), and activating downstream pro-survival (e.g., PI3K/Akt), pro-migration/invasion (e.g., MAPK/JNK, uPA/uPAR) pathways.