REG4 also known as Regenerating islet-derived protein 4. This protein is calcium-independent lectin displaying mannose-binding specificity and able to maintain carbohydrate recognition activity in an acidic environment. It may be involved in inflammatory and metaplastic responses of the gastrointestinal epithelium. Recombinant human REG4, fused to T7-tag at N-terminus, was expressed in E.coli.