In a recent study, the drugs, oligo-floxuridine (FdU) and monomethyl auristatine E (MMAE), were chemically coupled to exotoxin A from Pseudomonase aeruginosa and diphtheria toxin from Corynebacterium diphtheria, respectively, to form self-assembled protein NPs with an average size of 50 nm targeting CXCR4+ tumor cells [95]. This evidence concerns the gene CXCR4 and neoplasm.