(A) Binding intensity at BRD4 peaks, categorized by type 1 versus type 2, during interphase, mitosis, or mitosis treated with 1-h 250 nM JQ1. Means ± 95% CI. (B) Schematic describing how mitotic bookmarking function was tested with rapid competitive inhibition to remove BRD4 from chromatin only during mitosis. (C) Comparison of qRT-PCR quantities for 16 primary transcripts after treatment with 10 μM JQ1 or DMSO during mitosis. Dotted black line is equality; dotted red lines show 2-fold change. Data are normalized to glyceraldehyde 3-phosphate dehydrogenase (GAPDH)-mature transcript and to mean quantity across all time points. (D) Pol II ChIP-qPCR after 1 h of 250-nM JQ1 versus DMSO treatment shows minimal changes in binding. Means ± SEM, n = 3. (E) Pol II TSS rpkm at 385 type-2-associated genes in mitotic cells treated with 250 nM JQ1 versus DMSO. (Left) Mean ± SEM. (Right) Scatterplot of log2 (rpkm). Line is equality, and contours are 2D kernel-density estimations.