GRPR and cancer: We alsodisclosed that binding of Ir-H to BN3 notablyenhances its selectivity toward cancer cells overexpressingGRPR, as reflected by the lower IC50 values of the resultingmetallopeptide Ir-BN in PC-3 cells compared to A549 cells,which exhibit low GRPR expression, and importantly, to noncancerousMRC-5 fibroblasts.