The impact of PPARγ on cancers is complex and bidirectional, PPARγ acts as a tumor promoter by induction of lipogenic gene ACLY, MIG12, FASN, and NR1F1, stem cell-related gene KLF4, ALDH and upregulation Nox1 ROS, and VEGF. The gene discussed is KLF4; the disease is neoplasm.