(A) ALL-SIL cells were transfected with a STAT5-luciferase construct (NCAM-luc) and treated with vehicle, JQ1 (1 μM), iBET (1 μM) or the enantiomer (−)-JQ1 (1 μM), after which STAT5-dependent gene expression was determined by dual luciferase assay. (B) DU528 cells were treated with vehicle, JQ1 (1 μM) or iBET (1 μM) for 6 hours, after which expression of the indicated STAT5 target genes was determined by quantitative RT-PCR. HEL cells (C, E) or ALL-SIL cells (D) were treated with the indicated shRNA constructs targeting BRD2, after which expression of the indicated genes was determined by quantitative RT-PCR.