In this paper, KLFs have been summarized via systematic reviews, with either a promoting (KLF4 ∼ KLF8, KLF15) or an inhibiting (KLF2 ∼ KLF6, KLK9 ∼ KLF12 and KLF17) roles, which should be useful to monitor lung cancer progression or understand its mechanisms. The gene discussed is KLF4; the disease is lung cancer.