Krüppel-like factors (KLF) is a family of transcription factors with three highly conserved C2H2 zinc finger structures at the carboxyl end, which is widely found in various tissues and has been shown to control essential cellular processes such as proliferation, apoptosis, migration, and differentiation.35,36 KLF9, one of the most important members of the KLF family, regulates gene expression by activating or inhibiting promoters with rich GC boxes.37 Aberrant expression of KLF9 leads to cellular disorders and influences the occurrence and development of various diseases, including cancer. The gene discussed is KLF9; the disease is cancer.