Wang et al. previously showed that atRA induces the tumor suppressor gene XAF1 expression through an interferon regulatory factor-1 element in colon cancer [33], and Woo et al. recently reported that atRA induces expression of the tumor suppressor gene E-cadherin via inhibition of DNA methylation in HCT116 cells [34]. The gene discussed is IRF1; the disease is malignant colon neoplasm.