GPR68 and ovarian carcinoma: OGR1-family G protein-coupled receptors (GPCRs), including ovarian cancer G protein-coupled receptor 1 (OGR1 or GPR68), G protein-coupled receptor 4 (GPR4), T-cell death-associated gene 8 (TDAG8 or GPR65), and G2A, have initially been reported as receptors for lysolipids, such as sphingosylphosphorylcholine (SPC) and lysophosphatidylcholine (LPC) [1–3]; however, lipid actions have not always been confirmed [4, 5].