Another family of surface receptors that has been commonly targetedfor enhanced detection of cancer cells are growth factor receptors,including the epidermal growth factor receptor (EGFR) and the vascularendothelial growth factor receptor (VEGFR), which play important rolesin tumor growth and cancer progression (Figure 2c).51 Unlike FR-α,these receptors have been most commonly targeted using fluorescentlylabeled antibodies. This evidence concerns the gene KDR and cancer.