GPR68 and ovarian cancer: VECs and VSMCs within arteries express proton-sensing G protein-coupled receptors (GPCRs), including the ovarian cancer G protein-coupled receptor (OGR1) (also known as GPR68), GPR4, G2 accumulation protein (G2A) (also known as GPR132), and T-cell death-associated gene 8 (TDAG8) (also known as GPR65) [25,26,27,28,29].