PDCD5 (programmed cell death 5) is a multifunctional protein with primary roles in apoptosis regulation and protein folding. As an apoptosis-promoting protein, PDCD5 accelerates programmed cell death by upregulating pro-apoptotic factors (BAX, caspase-3, P53) while downregulating anti-apoptotic BCL-2, and induces cell cycle arrest at G2/M phase 1. Beyond apoptosis, PDCD5 functions as a TRiC/CCT chaperone complex regulator, promoting substrate release by competing with PhLP2A to facilitate cilium and flagellum biogenesis 2. PDCD5 rapidly translocates from cytoplasm to nucleus upon stress signals, where it regulates transcription factors including TIP60, HDAC3, MDM2, and TP53, and participates in immune regulation via the PDCD5-TIP60-FOXP3 pathway 3. Clinically, PDCD5 downregulation is strongly associated with tumorigenesis across multiple cancer types. Lost or decreased PDCD5 expression in epithelial ovarian carcinomas correlates with advanced FIGO stage and poor survival 4. Similarly, low PDCD5 expression in chondrosarcoma predicts aggressive disease and shorter overall survival 5. Therapeutically, PDCD5 overexpression via adenoviral gene delivery synergizes with chemotherapy, enhancing daunorubicin and idarubicin sensitivity in leukemic cells with reduced toxicity 6 7. Altered PDCD5 levels are also detected in Alzheimer's disease plasma 8, suggesting broader pathophysiological relevance beyond cancer.