NRP1 and neoplasm: In recent decades, we have tried to inhibit tumor growth by selectively blocking the beginning of the cascade at the receptor level (such as in the use of anti-epidermal growth factor receptor (EGFR) inhibitors), blocking the middle of the cascade (such as with anti-RAF or anti-mTOR inhibitors) or blocking extracellular ligands (such as vascular endothelial growth factor (VEGF)) before contact with the transmembrane receptors expressed on tumor cells.