Gap 26 is a connexin mimetic peptide corresponding to the residues 63-75 of connexin 43, which is a gap junction blocker. IC50 & Target: Gap Junction Protein^[1] In Vitro: Gap 26 is corresponding to the residues 63-75 of connexin 43, which is a gap junction blocker. Gap 26 (100-300 μM) dose-dependently reduces the rhythmic responses of rabbit superior mesenteric arteries, with IC₅₀ of 28.4 ± 3.4 μM^[1]. Gap 26 abolishes the inositol-1,4,5-trisphosphate (InsP3)-triggered ATP response and reduces the ATP release, but has no effect on gap junctional coupling^[2].