A GPCR that acts directly on MaR1 has not yet been identified. However, MaR1 blocks TRPV1-mediated currents in neurons, acts as a ligand for the retinoid-associated orphan receptor α (RORα), and inhibits TLR4 signalling (Fig. 2) (Park 2015), Chiang et al. found that MaR1 can activate LGR6, a member of the glycoprotein hormone receptor subfamily of rhodopsin-like GPCRs (Chiang et al. 2019b), which initiates cAMP, impedance changes, and stimulate an innate immune response against PMNs, monocytes and macrophages (Chiang et al. 2019b).