IL-6 and IL-10 counteract the rapamycin-induced growth arrest. (A) Western blot analysis of 4E-BP1 and eIF4E after immunoprecipitation with ⁷methyl-GTP Sepharose. Samples are drawn at indicated times after exposure of BC-3 cells to 50 nM rapamycin. (B-C) Shown is the concentrations in picogram per milliliter for the indicated cytokine in the vertical axis and dilution of spent medium of 4 days after addition of rapamycin (open symbols) or vehicle (closed symbol) on the horizontal axis for the cell lines BC-1 (circles) and BCBL-1 (squares) as determined by ELISA. (D-E) Relative growth in percentage after 4-day culture in 50 nM rapamycin and the indicated concentrations of either IL-6 or IL-10 as determined by MTT assay.