Although vasodilatation is elicited by a majority of the migraine provoking agents [6, 14, 20], the vascular response does not seem essential for generating delayed migraine attacks, as robust vasodilators, such as the vasoactive intestinal polypeptide (VIP) or adrenomedullin, do not induce migraine [21, 22]. The gene discussed is VIP; the disease is migraine disorder.