CALCA and migraine disorder: Activation of trigeminovascular afferents provokes antidromic release of calcitonin gene-related peptide (CGRP), substance P (SP), and pituitary adenylate cyclase-activating polypeptide (PACAP); beyond mediating migraine pain, these peptides remodel vasculature, immune infiltrates, and extracellular matrix to facilitate GBM invasion.