Figure 1. The VIP family of peptides. Amino acid sequence identities with VIP are shown in red. VIP, vasoactive intestinal peptide; PACAP, pituitary adenylate cyclase activating peptide; PHI, peptide histidine isoleucine; PHV, peptide histidine valinamide; GHRH, growth hormone releasing hormone; GIP, gastric inhibitory peptide