HDAC1 and cardiac hypertrophy: Previous studies have reported that Klf4 signal cascades may be a target for certain HDACs during HDACi-induced prevention of cardiac hypertrophy.21,22 Coincidentally, we found that knockdown of HDAC1 increased the accumulation of acetylated histone H3 and H4 in the promoter region of Klf4, which facilitated the binding of Klf4 to its own promoter and upregulated its expression.