A simple explanation for preferential deacetylation at TSS and super-enhancer regions after butyrate treatment may be a non-selective redistribution of histone acetylation that affects such regions more profoundly due to their extensively acetylated nature. However, a substantial number of established highly enriched H3K27Ac peaks either increased in acetylation levels or – even more frequently – were unaffected by butyrate treatment (representative examples in Supplementary Fig. 6B). For example, only ~31% of the 500 most extensively acetylated sites in the mast cell genome were hypo-acetylated by butyrate after 3 h (Supplementary Fig. 6C). Nevertheless, most hypo-acetylated peaks (~74%; 890 out of 1203) after 3 h treatment originated from the 5000 strongest H3K27Ac peaks (Supplementary Fig. 6D). Thus, butyrate-induced hypo-acetylation selectively targets a subset of extensively acetylated peaks.