Next we generated stable ASIP-secreting B16-F10 cells using a lentivirus vector since calcium and lipid agent transfection efficiencies in the tumor cells were less than 15% and their intrinsic drug resistance extended to as great as 2000 μg/ml G418 and 5 μg/ml puromycin, precluding selection for ASIP expressing cells using linked drug resistance (data not shown). Here, ASIP is linked to neoplasm.