PAQR7 and breast cancer: PLA of mPRs overexpressed in several breast cancer cell lines with G proteins confirms previous results from co-immunoprecipitation and G protein inhibitor studies that indicate mPRα, mPRβ, and mPRγ are coupled to inhibitory G (Gi) proteins, whereas mPRδ and mPRε are coupled to stimulatory G (Gs) proteins [21].