NRP1 and neoplasm: iRGD peptide (CRGDKGPDC) helps to promote extravasation and specific penetration by interacting with integrin αvβ3 (αvβ3) or αvβ5 and neuropilin‐1 (NRP‐1) on the tumour vascular endothelium and tumour cells, which shows great potential for tumour targeting [16, 17].