HDAC family has four subclasses including I, II, III and IV. Histone deacetylase 1 (HDAC1) is a unique member of the classes I HDACs that has been shown to be involved in gene transcription, transcriptional regulation, cell cycle progression and developmental events by controlling both enzyme activity and epigenetics of key proteins [PMID: 16289629]. HDAC1 is the most abundant member of the class I HDACs in pulmonary endothelial cells [PMID: 34264338], regulating the enzymatic activity and epigenetics of key proteins to adapt to external stimuli. It can efficiently decrotonylate this relatively less abundant histone modification [PMID: 29317660].