GPR68 and hematopoietic and lymphoid system neoplasm: Four members of the group of GPCRs, namely GPR4, TDAG8 (GPR65), OGR1 (GPR68), and G2A (GPR132), are proton sensors [149], and at this point, it is worth mentioning that TDAG8 has been shown to act through Gα13/Rho signaling in blood cancer cells [61].