ChIP-seq assays showed that acetylation of H3K27 at cell cycle/mitochondrial gene promoters and super-enhancers of genes relevant for multiple myeloma biology (c-MYC, BCL-XL, CCND2, IRF4, MCL1, PIM1, PRDM1, and XBP1) was mildly increased in HDAC3 knockdown cells compared with nonsilencing cells. The gene discussed is XBP1; the disease is plasma cell myeloma.