Lentivirus was packaged in 293T HEK cells grown in DMEM/F12 (Invitrogen) supplemented with 10% FBS (Gemini). The 293T cells cultured in the 15-cm dish were transfected with a solution consisting of 12.2 μg lentiviral DNA, 8.1 μg MDL-gagpol, 3.1 μg Rev-RSV, 4.1 μg CMV-VSVG, 500 μl of Opti-MEM (Invitrogen) and 110 μl PEI (1 μg ml−1). Medium was changed after 12 h and the virus was harvested at 72 h after transfection.
