Immunohistochemical studies on human colon cancer specimens revealed inter- and intratumoral heterogeneity for the expression of different receptor tyrosine kinases (RTKs), including EGFR, vascular endothelial growth factor receptor-2 (VEGFR2), and platelet-derived growth factor receptor β (PDGFRβ). This evidence concerns the gene KDR and malignant colon neoplasm.