LPS initiates endothelial apoptosis only in the presence of CHX. (A) HMEC-1 cells were treated with LPS for 15 hours in the presence or absence of CHX (50 μg/mL). Each data point is the proportion of viable cells with respect to cells treated with medium only. Results are the means + SD of three experiments. (B) HMEC-1 cells were treated with LPS (100 ng/mL) only, LPS and CHX (50 μg/mL), or CHX only for 15 hours and harvested DNA was separated on an ethidium bromide-stained agarose gel. The lane on the left is a 100-bp molecular weight marker.