STAT3 and cancer: The increased ROS levels in cancer cells are a results of changes in mitochondrial metabolism [96, 99] that trouble cellular signaling pathways [100, 101], which are mainly mediated by the transcription factors NF-κB and STAT3, hypoxia-inducible factor-1α, kinases, growth factors, cytokines, and other enzymes [90] associated with cellular transformation, inflammation, tumor cell survival, proliferation, invasion, angiogenesis as well as metastasis of cancer [90].