Cancer stem cells (CSCs), also termed tumor-initiating cells (TICs), are a small population of stem cell-like cancer cells that can initiate tumors in vivo.4 CSCs are the major source of cancer initiation, relapse, and drug resistance.4 The stemness-related proteins SOX2, OCT4, NANOG, KLF4, and c-Myc induce pluripotency in somatic cells,5 and also contribute to tumorigenesis5–16 and CSCs6–10 in cancers, including NSCLC. Here, KLF4 is linked to cancer.