L-flow inhibits 15d-PGJ₂-induced endothelial apoptosis via p53 down regulation. (A) HUVECs were exposed to L-flow followed by treatment with 15d-PGJ₂ for 8 h. Protein expression was determined by Western blotting using anti-p53 and anti-tubulin antibodies. (B) HUVECs were transfected with either control or p53 siRNA (si-p53) for two days. Cells were then exposed to 10 µM 15d-PGJ₂ for 8 h. The expression of cleaved caspase 3, p53, and tubulin was detected by Western blotting with the respective antibodies. (C) Cell viability was determined by MTT assay. Data are expressed as the mean±SD from three independent experiments. ^*P<0.01. L-flow, steady laminar flow; 15d-PGJ₂, 15-deoxy-Δ(12,14)-prostaglandin J₂; HUVECs, human umbilical vein endothelial cells.