KDR and cancer: Other examples include antibodies or their fragments that bind to the variety of cancer- and cancer microenvironment-associated proteins (EGFR, HER2, PD-1, CD8, PD-L1, VEGFR, etc.)[26,27,28,29,30], and peptides, such as internalizing iRGD [31,32] that binds to the integrins and is internalized by the neuropilin-1 overexpressed by the endothelium of different cancers, or the non-internalizing RGD peptide [33,34] that binds to integrins.