The inhibiting roles of some KLFs (KLF2 ∼ KLF4, KLF6, KLF9 ∼ KLF12, KLF17) were detected in cancer tissues by exerting transcriptional inhibition, activating P53 or downstream tumor suppressor genes, inducing cell apoptosis, inhibiting key molecules of signal pathway to prevent EMT transformation, invasion or metastasis of cancer cell, etc [72]. The gene discussed is KLF9; the disease is cancer.