NRP1 and neoplasm: Indeed, specific deletion of Nrp-1 in Treg cells (Nrp1f/fFoxp3Cre mice) or blockade of Nrp-1 with Sema4a mAb, Nrp-1 mAb and Sema4a-Ig significantly decreased tumor growth in the B16F10 melanoma mouse model (29, 89).