KLF4 and lung cancer: Recently, additional studies have demonstrated stemness increased in different microenvironments, and transcription factors such as Sox-2, Oct-4, Klf-4 and Nanog were reprogrammed into both normal tissues including human dermal fibroblasts [42] and Müller glia cells [43], and tumors including lung cancer [44], colon cancer [45] and ovarian cancer [46].