Effect of MEK1/2 inhibitor on saquinavir accumulation, TNF-α and nitrite release. Saquinavir accumulation and inflammatory mediator release was determined following incubation of HAPI cells with a cell permeable MEK1/2 inhibitor U0126 (A). Accumulation of [3H]saquinavir (50 nM) in the presence and absence of 10 ng/ml LPS and 10 μM U0126 at one hour at 37°C. Release of TNF-α (B) and nitrite (C) into the medium following 24 hour incubation with 10 ng/ml LPS in the presence of U0126. Each data point represents mean ± SE of at least three separate experiments with three replicates included per experiment; *P < 0.05, significantly different from untreated control cells.