The REG4 gene encodes a deduced 158-amino acid protein with an N-terminal signal peptide of 22 amino acids and a predicted molecular mass of 18.2 kD. REG4 maintains conservation of the 6 cysteine residues present in other known members of the REG family. By Northern blot analysis of intestinal mucosa from 12 individuals with inflammatory bowel disease, Hartupee et al. (2001) identified a 1.1-kb REG4 transcript in all samples.

Control specimens had low but detectable expression of REG4. REG4 expression was significantly upregulated by inflammation and tissue injury associated with active Crohn disease and ulcerative colitis. RNA dot-blot analysis showed that most of the tissues expressing REG4 are in the gastrointestinal tract, i.e., colon, small intestine, stomach, and pancreas.