KLF4 and cancer: In addition to HIF1α that is a known oncogenic factor regulating angiogenesis of the tumor tissue and the hypoxic growth of the cancer cells, a number of other well-documented oncogenes and stemness genes for cancer stem cells, including MYC, SOX2, KLF4, TCF19, NAMPT, BACH1, ZEB1, CD44, EGFR, etc., also showed an enhanced enrichment of Nrf2 binding to the Nrf2 binding elements either in upstream, downstream or promoter region of these genes in response to arsenic treatment.