<p>(A) In ligand-free situation, the disturbance of the plasma induced entocytosis of PAC1 dimers, which triggered the activation of the basal activity of PAC1 dimers involved with Wnt/β-catenin signal pathway to protect the cells against apoptosis. (B) In ligand-dependent manner, the binding of the ligands for PAC1 disrupted the dimerization of PAC1 and induced internalization of PAC1 monomer, which inhibited the basal activity of PAC1 dimers.</p
