The effect of PI3K and MEK1/2 inhibition on cell viability during RV infection. Serum-starved RK13 cells were mock infected or infected with RV at an m.o.i of 4 PFU/cell with or without LY294002 (30 μM) or U0126 (15 μM). At indicated time points cell viability was determined by XTT assay. Tetrazolium salt (XTT) and electron coupling reagent were added directly to cells, and after 24 hours the absorbance at 405–690 nm was determined. Data represent mean ± S.E. from three independent experiments.