PDGFRB and neoplasm: Such markers include CAIX that is upregulated in the hypoxic conditions in solid tumors,51 VEGFR2 being a driver for tumoral angiogenesis,52 and PDGFR, that is expressed on activated pericytes and fibroblasts in tumor stroma.53 Imaging tracers for such markers could provide a more general imaging modality that in principle would be less restricted to tumor cell phenotype.