GRM4 and cancer: Overall, 3795 non-unique imageable genes (Supplementary Data 28) are up-regulated among 20 cancers of The Cancer Genome Atlas, including the glutamate metabotropic receptor GRM4 in breast cancer, the dopamine transporter SLC6A3 in renal clear cell cancer, the ionotropic glutamate receptor GRIN2D in colon cancer, the gamma-aminobutyric acid receptor GABRD in hepatocellular cancer and and the Epithelial Cell Adhesion Molecule EPCAM in cholangiocarcinoma (Fig. 5c(i) and Supplementary Fig. 7).