KLF4 and atherosclerosis: In contrast, promoter regions of atheroprotective genes such as oestrogen receptor 1/2 (ESR1/2), ATP-binding cassette transporter A1 (ABCA1), and kruppel-like factor 4 (KLF4) are often hypermethylated in atherosclerosis [43,48,50] and Kim et al. demonstrated higher methylation levels of genes involved in plaque progression and vulnerability such as autoimmune regulator 1 (AIRE1) and arachidonate 15-lipoxygenase (ALOX12), among others, in plaques than in non-plaque intima [51].