NRP1 and neoplasm: Intravenous iRGD was first used to target integrins in the tumor vasculature [109], and then iRGD was proteolytically proteolyzed into CRGDK/R, exposing the active CendR sequence and the binding of this sequence to NRP-1, which triggers transport channels across the vascular wall and tumor tissue surface (Transcytosis) [110].