REG1A (Regenerating islet-derived 1 alpha) is a member of the Reg family of secreted proteins with a C-type lectin domain. REG1A is associated with islet cell regeneration and diabetogenesis and may be involved in pancreatic lithogenesis. Due to variable glycosylation, pancreatic REG1A exists as multiple species of 16 -18 kDa. REG1A promotes the maintenance and growth of pancreatic islet β-cells and intestinal villi. It is upregulated in pancreatitis and some carcinomas. REG1A is an antigenic target in autoimmune diabetes.