In contrast to the effects of NRP1 knockdown, overexpression of NRP1 ΔC had no significant effect on PDGFR activity, consonant with our previous finding that this mutant had no effect on activation of PDGFR or VEGFR in U87 glioma cells,6 and indicating that the NRP1 cytosolic domain is not required for PDGFR activity in rat VSMC. This evidence concerns the gene PDGFRB and central nervous system cancer.