GPR68 and colitis: The orphan proton-sensing GPCRs, GPR4, GPR65 (TDAG8), GPR68 (OGR1) and GPR132 (G2A), all have recognized roles in colitis pathophysiology7,11 and other inflammatory and neuropathic pain conditions.12, 13, 14, 15 Although often classified with these receptors, GPR132 differs functionally and structurally, showing weak proton sensitivity and being primarily activated by oxidized fatty acids.16