KLF5 and lung cancer: Of these genes, human homologs of 4 genes including Inhibin, beta A (INHBA), Kruppel-like factor 5 (KLF5), Serine/threonine/tyrosine kinase 1 (STYK1), and stem cell marker ALDH1A1 are previously shown to be over-expressed in NSCLC and involved in lung cancer progression and tumorigenicity [16, 20–23].