REG3A and digestive system neoplasm: AMP secretion is triggered by the recognition of bacterial molecules by Toll-like receptors (TLRs), such as TLR4, and nucleotide-binding oligomerization domain-containing proteins (NODs), such as NOD2, which are membrane-bound receptors on enterocytes.22, 23 Humans express REG3A—also known as HIP/PAP (hepatocarcinoma-intestine-pancreas/pancreatitis-associated protein)—and REG3G, whereas Reg3b is only present in mice.