GSK690693 induces apoptosis in ALL cells. (A) I2.1, I9.2, A3, and Tanoue cells were treated with DMSO or varying concentrations of GSK690693 for 72 hours, and cell-cycle distribution was determined based on DNA content of propidium iodide-stained populations. (B) Representative histogram of cell-cycle analysis. Histograms illustrate cell cycle profile of DMSO- and GSK690693-treated I2.1 and Tanoue cells. (C) ALL cell lines were treated with DMSO or different concentrations of GSK690693 for 24 hours, and endogenous levels of cleaved caspase-3 were measured. (D) PARP cleavage was determined by Western blot analysis in ALL cell lines treated with DMSO or various concentrations of GSK690693 for 24 hours. (E) ALL cell lines were treated with DMSO or different concentrations of GSK690693 for 24 hours, and the caspase activity was measured using caspase 3/7 assay kit. Data represent relative luminescence signal (mean ± SD) for each cell line. (F) DNA fragmentation was measured in A3, I2.1, and Tanoue cells treated with DMSO or GSK690693 for 72 hours as described in “Methods.” Data represent a comparison between GSK690693 sensitive and insensitive cell lines.