Fig 1: Regulation of expression of LV gene components in the packaging cells(A) Expression of VSV-G, Rev, and Gag by the packaging cells (clone 3D4) was analyzed by western blots after induction with cumate and coumermycin. The same amount of total protein from the cell lysate was used for the analysis. Cells were harvested before (0) or after 24, 48, and 72 h of induction in the absence or presence of sodium butyrate (+B) (added 18 h post induction). 293SF-CymR/?R-GyrB cells were used as a negative control (CT). The position of molecular weight marker in kDa (MW) is indicated. The position of VSV-G, Rev, the Gag polyprotein (GagPP), and p24 is indicated. Note the presence of non-specific bands (*) in the negative control when using the anti-VSV-G antibody. (B) Analysis of the induction level for VSV-G, GagPP, and Gag p24. The western signal before and at 48 h post induction in the absence or presence of sodium butyrate was measured using a digital imaging system. The values were normalized to the signal of ß-actin obtained after stripping and incubating the membrane with an anti-actin antibody. The experiment was done in triplicate (N = 3). Value are the means ± SD. Means significantly different from each other: **p < 0.01, *p < 0.05.