Rapamycin inhibits mTOR in primary AML samples. (A-B) Patient samples were thawed and incubated for 16 hours in different concentrations of rapamycin as shown. As controls, U937 cells were similarly incubated. After incubation, cells were harvested, lysed, and analyzed for expression and phosphorylation of p70S6 kinase by Western blotting. (C-D) Patient samples were thawed and incubated for 16 hours in nothing (-), 0.1% DMSO (D), 10 μM etoposide (E), 10 μM rapamycin (R), or a combination of etoposide and rapamycin at the same concentrations (E + R). Cells were harvested, lysed, and analyzed by Western blotting.