Rapamycin and CCI-779 inhibit cytokine- and leukemia-induced BM-EC proliferation. BM-ECs were cultured in cytokine media/EGM2 (A-B) or 10% vol/vol leukemia plasma after a period of starvation (C-D); proliferation was measured using an MTS assay. Rapamycin (RAPA; A,C) and CCI-779 (B,D) were tested at the indicated doses. As control for putative solvent toxicity, DMSO was tested at concentrations equivalent to those present in the respective doses of RAPA, with no significant toxicity observed up to the DMSO amount present in 10⁴ ng/mL of the drug (data not shown). Results presented as proliferation index in percentage of control condition ± SEM of experiments using BM-ECs from 4 to 6 different donors. Plasmas from 8 to 10 different leukemia patients were used.