HTR6 and breast cancer: Based on the fact that genes that had been proven to be related to the progression of breast cancer including DRD1 and HTR7 were both Gsα protein-coupled receptors (GsαPCRs) (26, 27), and several studies had shown that Gsα protein was associated with malignant transformation of a variety of tumors (28–30), we further filtered the 20 candidate receptors and obtained three GsαPCRs, including DRD1, DRD5, and HTR6.