Effect of Akt phosphorylation on rheumatoid arthritis (RA) fibroblast-like synoviocyte (FLS) survival. LY294002, a potent PI3K (phosphoinositide 3-kinase) inhibitor, decreased Akt phosphorylation in a dose-dependent manner, and Bcl-2 levels were found to be closely correlated with phospho-Akt levels (a). When cells were treated with LY294002, the cytoprotective effect of heat shock protein 70 (Hsp70) knock-down disappeared (b). The experiments were performed using three RA FLS samples (a, b) in triplicate (b). The representative figures are shown. MTT, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide; siRNA, small interfering RNA.