However, since endothelial cells also express Fgfr3 (but not Fgfr4)26, and upregulate Fgfr3 expression in the absence of Fgfr127, it is possible that Fgfr3 could compensate for the Fgfr1 and Fgfr2 deficiency in tumor endothelial cells. This evidence concerns the gene FGFR1 and neoplasm.