LPS-induced inhibition of NPM1 proteolysis. (A) Macrophages obtained by M-CSF treatment of human peripheral blood monocytes for 6 days were left untreated (−) or exposed to LPS (1 mg/mL) for 24 hours (day 7) or 48 hours (day 8) before cell lysis and immunoblot analysis of indicated proteins (HSC70, loading control). (B) Flow cytometric analysis of active caspase-3/7 in macrophages 48 hours after LPS treatment. (C) Cathepsin B activity was measured as in Figure 2D 48 hours after LPS treatment. Each panel is representative of at least 3 independent experiments in triplicate (****P < .001).