I-BET151 inhibits transcription of oncogenic MYC by interfering with BRD4-dependent transcriptional activation. (A) Time- and dose-dependent effect of I-BET151 on OPM-2 myeloma cell proliferation (n = 3). (B) MYC transcript levels after 6 hours of treatment with different doses of I-BET151 and I-BET762, their inactive enantiomer I-BET768, and JQ1. Data were normalized to vehicle control (n = 3). (C) MYC transcript levels after 6 or 24 hours of treatment with two different doses of I-BET151 or vehicle (n = 3). (D) chromatin immunoprecipitation (ChIP)–RQ-PCR analysis of BRD2, -3 and -4 binding onto the IGH enhancer in OPM-2 cells at 0, 2, and 4 hours after treatment with 1 μM I-BET151. Data are shown as percent of input (n = 3). (E) ChIP–RQ-PCR analysis of CDK9, PAF, and RNA Pol II binding onto the IGH enhancer of OPM-2 cells. Background IgG binding as percentage of input for ChIP assays in (D) and (E) is also shown (n = 3). Data are shown as mean ± SEM.