As you know, histone modifications such as acetylation and methylation are important in regulating gene expression. In addition to methylation and acetylation, various histone modifications have been discovered in recent years, including serotolyration and glutarylation. Here, the authors discovered a new modification called histone lactylation and explored its function. --- The authors first searched for novel histone modifications by MS. As a result, they identified new histone modifications "lactylation" which use lactate as a substrate. And they found that this histone lactylation promote gene expression by cell-free system. -- A very interesting aspect of this lactylation is that it uses lactate, a glycolytic metabolite, as a substrate. Therefore, the authors further investigated for a relationship between intracellular metabolism and lactylation. To this end they manupulated intracellular metabolism by chemical compounds.