Effect of TNF-α, PI3K/Akt, P38 MAPK and ERK1/2 inhibitors on cell proliferation. Cell proliferation was measured MTT 24 hrs after cells were pre-treated with vehicle (A), LY294002 (B), Wortmannin (C), SB203580 (D) and PD98059 (E) at 1 and 5 μM for 1 hr, respectively, followed by the challenge with TNF-α at 1 ng/ml.