iRGD: A Promising Peptide for Cancer Imaging and a Potential Therapeutic Agent for Various Cancers

Figure 1

The key steps in the tumor-targeting process of the iRGD peptide. First, iRGD peptides (CRGDK/RGPD/EC) bind to integrins (αvβ3 and αvβ5). Second, the peptide is proteolytically cleaved in the tumor to produce CRGDK/R and expose the activated CendR motif (R/KXXR/K) at the C-terminal end. Third, the CendR motif binds to NRP-1 to trigger tumor tissue penetration. T: tumor.