Encoded by human oncogene VIP Gene (Glucagon-Secretin Family), VIP is a 170-amino acid 19 kD (precursor) octacosameric gastrointestinal peptide and a neuroendocrine mediator in CNS cholinergic neurons and PNS peptidergic neurons. VIP also affects B- and T cells directly. Prepro-VIP contains VIP and 27-amino acid PHM27. A neuropeptide in the lymphoid microenvironment, VIP has anti-inflammatory action, modulates innate and adaptive immunity, causes vasodilation, lowers arterial blood pressure, stimulates myocardial contractility, increases glycogenolysis, and relaxes the smooth muscle of trachea, stomach and gall bladder. VIP promotes TH2 differentiation and inhibits TH1 responses by regulating macrophage co-stimulatory signals. (OMIM, Swiss-Prot, LocusLink, and NCI)