CPB1 encodes carboxypeptidase B1, a pancreatic secretory enzyme with metallocarboxypeptidase activity that cleaves C-terminal basic amino acids from proteins 1. The protein functions as a digestive enzyme in the pancreas, where variants affecting proper protein secretion can induce endoplasmic reticulum (ER) stress in pancreatic acinar cells 12. Functionally impaired CPB1 variants that cause ER stress are significantly associated with increased pancreatic cancer risk, with odds ratios ranging from 7.02 to 9.51 across studies 12. Beyond pancreatic function, CPB1 appears to play roles in other tissues - it serves as a biomarker distinguishing ductal carcinoma in situ (DCIS) from invasive breast cancer, with high expression correlating with better survival outcomes 3. In lens epithelial cells, CPB1 promotes apoptosis and oxidative stress through interactions with transcription factor BACH2, contributing to age-related cataract pathogenesis 4. The gene has also been identified in proteomic networks associated with chr3 obstructive pulmonary disease phenotypes 5. Clinically, CPB1 variants represent important genetic risk factors for pancreatic cancer development, particularly those causing cellular stress responses.