(i) PSMA is expressed at low levels in the salivary glands, kidneys and small intestine, with PSMA-targeted radiotracers showing uptake in the salivary glands, in both mice and human patients.34–36 Indeed, the salivary glands are considered dose-limiting organs, and uptake of radiotherapeutic PSMA-targeted radiopharmaceuticals can lead to xerostomia in prostate cancer patients.36 This evidence concerns the gene FOLH1 and prostate cancer.