OSI-027 inhibits ³H-thymidine incorporation and diminishes viable cell mass in cultures of malignant lymphoid cells. (A-B) After lymphoid cell lines were treated for 48 hours with OSI-027 or rapamycin as indicated, ³H-thymidine incorporation into DNA was assayed. (C-E) After lymphoid cell lines (C) or primary clinical samples from patients with the indicated lymphoid neoplasms (D-E) were treated for 5 days with OSI-027 or rapamycin as indicated (C-D) or with 5μM OSI-027 versus 10nM rapamycin (E), MTS reduction was assayed. MTS reduction of cells treated with diluent (0.1% DSMO) for 5 days was set at 100% in each assay. Error bars in panels A through C, mean ± SEM of 3 independent assays.