REG1A and colorectal carcinoma: Of the REGs, only REG4 is constitutively expressed in the colon but several REG proteins are aberrantly expressed in inflammatory pathologies including IBD, where REG1A, REG1B and REG3A are all expressed at the intestinal crypt base by metastatic Paneth cells [39]; REG1A and REG1B have also been reported to be concomitantly upregulated in CRC [40], but no mechanistic rationale has been provided previously.