Recent study indicated that chromatin modification through H3K9 methylation regulates Sox2 expression in lung cancer.27 Because KDM3A is known to activate gene expression through H3K9me2 demethylation,28, 29, 30 we checked the binding of KDM3A and the level of its substrate, H3K9me2 on Sox2 promoter by ChIP assay. The gene discussed is KDM3A; the disease is lung cancer.