Model depicting cross-talk between histone H4 acetylation, DNA methylation and H3K9me2. The black arrow shows the TSA-mediated pathway, and the red arrow displays the 5-AC-mediated pathway. TSA induces an increase in H4ac, which subsequently causes a decrease in H3K9me2 and DNA methylation. 5-AC causes a decrease in DNA methylation, which is followed by an increase in H4ac and a decrease in H3K9me2. DNA methylation and H4ac both precede and control H3K9me2, while H4ac and DNA methylation affect each other. H3K9me2 could also feed back on H4 acetylation or/and DNA methylation (dashed red and black arrows).