Emerging studies have demonstrated that KLF9 is commonly downregulated and serves as a tumor suppressor in multiple malignancies, which is related to the poor prognosis of cancer patients with downregulated KLF9 expression.38–40 Fu et al.41 reported that KLF9 mRNA and protein levels were decreased in HCC tissues compared with normal liver tissues and that the upregulation of KLF9 has anti-proliferative and pro-apoptotic properties in HepG2 cells. This evidence concerns the gene KLF9 and cancer.