Transfection of HEK293 cells mediated by Chi/M-VLP at (a) 2 μg/109 M-VLPs, (b) 4 μg/109 M-VLPs, (c) 7 μg/109 M-VLPs, (d) 10 μg/109 M-VLPs. Cells were incubated with hybrid vectors at 4 C or 37 C as indicated for 4 h following which the vectors were removed and replaced with fresh media, and the cells were incubated at 37 C for the remainder of the experiment. Luciferase activity (RLU/mg total protein) was normalized to the corresponding values 48 h post-transfection at 37 °C. Cellular uptake of Chi/M-VLP at (e) 2 μg/109 M-VLPs, (f) 4 μg/109 M-VLPs, (g) 7 μg/109 M-VLPs, (h) 10 μg/109 M-VLPs at 4 °C and 37 °C for 4 h as with the transfections. Uptake of Chi/M-VLP was normalized to the corresponding values 8 h post-transfection at 37 °C. Error bars represent SD, n=3.