CMKLR2 and ovarian cancer: Many GPCRs [e.g., parathyroid hormone 1 receptor (PTH1R) and calcium-sensing receptor (CaSR)] can promote osteoblast differentiation, and osteoclasts also express many GPCRs [e.g., calcitonin receptor (CTR) was able to inhibit bone formation in normal bone metabolism, and ovarian cancer G-protein coupled receptor 1 (ORG1) has also been found to be promoted on osteoclast differentiation] (30–33).