NRP1 and Familial prostate cancer: To study the effect of peptide coating on cellular uptake of PS, we incubated FAM‐labeled PS with cultured PPC‐1 and M21 cells—a well‐established system that has been used for CendR peptide based affinity targeting in vitro studies.[40, 41] PPC‐1 human primary prostate cancer cells have elevated expression of NRP‐1 (Figure S20).