A total of 3×105 293T cells were transfected with 1.5 mg of the four protease-recombinant plasmids at 0, 0.6 and 2 mM tipranavir. Twentyfour hours post-transfection, GFP-positive cells were sorted, harvested and lysed. Protein quantification was performed using the bicinchoninic acid assay (Pierce). Protein samples were run using 4%–12% polyacrylamide
electrophoresis gels (Invitrogen) and blotted onto nitrocellulose membranes using the iBlotTM Dry Blotting System (Invitrogen). After blocking, membranes were incubated overnight with rabbit polyclonal antibodies against eIF4GI and PABP or monoclonal antibodies against GFP, HIV-1 protease, actin and REF-1. After washing, membranes were incubated with antirabbit or antimouse goat antibodies labelled with horseradish peroxidase for 50 min and then revealed with ECL-Plus
solution (Amersham Biosciences).