iRGD peptide (amino acid sequence: CRGDKGPDC) The iRGD peptide enhances the extravasation and specific penetration into tumors due to its high affinity for integrins (αvβ3, αvβ5) and neuropilin-1 (NRP-1) on tumor vascular endothelium and tumor cells, showing significant potential for tumor targeting [215,216]. Here, NRP1 is linked to neoplasm.