On the other hand, activation of GPR37 by PD1 modulates macrophage-mediated phagocytosis by increasing intracellular calcium mobilization related to signal transduction mediated by Gi/o subunits, ERK and PI3K/AKT, all involved in the resolution of pro-inflammatory and neuropathic pain states [74,93,116,117]. Here, GPR37 is linked to neuropathic pain.