ERBB2 and breast cancer: In multiple molecular subtypes of breast cancer, including luminal A, luminal B, HER2, and basal subtypes, each tumor sample overexpressed several GPCRs that couple to Gi/o, Gs, Gq/11, G12/13, or unknown G proteins (Supplemental Figure 1, A–E; supplemental material available online with this article; https://doi.org/10.1172/jci.insight.150532DS1), but no single GPCR was overexpressed in all samples.