Peptide-conjugated liposomes containing doxorubicin or vinorelbine were prepared as described in other studies [26, 27] . Briefly, the peptide was coupled to NHS-PEG-DSPE [N-hydroxysuccinimido-carboxyl-polyethylene glycol (MW, 3400)-derived distearoylphosphatidyl ethanolamine] (NOF Corporation, Japan) in a 1:1.5 molar ratio. The reaction was completed and confirmed by quantitation of the remaining amino groups using TNBS (Trinitrobenzenesulfonate) reagent (Sigma, MO, USA). Doxorubicin and vinorelbine were encapsulated in liposomes through a remote loading method at a concentration of 1 mg of drug per 10 mmol phospholipids. Peptidyl-PEG-DSPE was transferred to pre-formed liposomes after co-incubation at a transition temperature of the lipid bilayer. There were 500 peptide molecules per liposome as described previously [48] .