Studies have shown that transcription factors such as SOX-2, OCT-4, KLF-4, Nanog and Lin-28A contribute to tumor cell dedifferentiation.7,8,10,11,13 Therefore, we first detected whether hypoxia promoted an increase in SOX-2, OCT-4, KLF-4, Nanog and Lin-28A expression at the mRNA and protein levels. The gene discussed is KLF4; the disease is neoplasm.