Monocyte purity, apoptosis, and susceptibility to LT. Red = CD14+ monocytes. Green = CD14-lymphocytes. A.) Forward and side scatter analysis of purified fixed human monocytes showing the monocyte population as compared to total population. B.) CD14 Pacific Blue and forward scatter analysis of fixed purified human monocytes showing >85% monocytes. C.) PI and annexin-FITC analysis of CD14 + monocytes after a 4 h incubation showing 99.0% viable cells indicated in quadrant 3. D.) PI and annexin-FITC analysis of CD14 + monocytes after a 4 h LT treatment showing 99.1% viable cells indicated in quadrant 3. HeLa cells or human monocytes were left untreated or treated with 500 ng/mL LT for 4 h at 37°C. Samples were lysed, run on SDS-PAGE, transferred to PVDF membrane, and probed with indicated antibodies. Both MEK3 and MEK1 were cleaved by LT while control cells showed no MEK cleavage. β-actin loading controls show equivalent loading of both control and LT treated cells.