Antimicrobial peptides (AMPs) are an ancient class of short polypeptides present in a large number of species in nature with a variety of functions.1 PFR (PFWRIRIRR-NH2) is one kind of AMP identified among the derivatives of lactoferrin.2 Our previous results showed that PFR inhibited the proliferation of human acute myeloid leukemia (AML) HL60 cells potentially without toxicity against normal cells. This evidence concerns the gene LTF and acute myeloid leukemia.