A couple of studies that evaluated the effect of 2-(phosphonomethyl)pentanedioic acid (2-PMPA), a PSMA inhibitor, in mice using 125I- and 111In-based PSMA ligands, found a near total reduction in PSMA uptake in the kidneys, but tumour uptake was still compromised [66, 67]. This evidence concerns the gene FOLH1 and neoplasm.