PDCD2L (programmed cell death 2-like) is a conserved protein with primary functions in ribosomal biogenesis and apoptotic regulation. It functions as a chaperone for ribosomal protein uS5 and associates with 40S ribosomal subunit precursors, shuttling between nucleus and cytoplasm via CRM1-dependent nuclear export 1. Its function appears redundant with its paralog PDCD2, as PDCD2L-null cells accumulate free 60S subunits indicating impaired 40S availability 1, and PDCD2L and PDCD2 function redundantly in 40S production 2. PDCD2L plays a critical role in post-implantation embryonic development, as Pdcd2l knockout mice die during embryogenesis (days 12.5-17.5), demonstrating essential developmental functions beyond ribosomal roles 3. In disease contexts, PDCD2L promotes apoptosis in pancreatic β cells through FoxO1-mediated transcription during palmitate-induced stress, contributing to β cell failure in type 2 diabetes 4. Clinically, PDCD2L is significantly upregulated across multiple cancers and associates with poor prognosis in hepatocellular carcinoma, colorectal cancer, and gastric cancer [PMID:39707202; 5; 62]. In hepatocellular carcinoma, BTF3 upregulates PDCD2L transcriptionally, promoting proliferation and apoptosis inhibition via p53 pathway restraint 7. PDCD2L knockdown reduces cancer cell proliferation, migration, and invasion [PMID:35216602; 62], suggesting potential as a therapeutic target. Additionally, PDCD2L functions as a positive regulator of endothelial apoptosis under low shear stress conditions relevant to atherosclerosis 8.