ANPEP and cancer: Chen et al. designed a nanoparticle with 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[folate(polyethylene glycol)-5000] (DSPE-PEG-5000) and an asparagine-glycine-arginine peptide to target aminopeptidase N (CD13), a protein involved in cancer invasion, angiogenesis, and metastasis.