SNAI1 and cancer: Concerning HIF-1α, it has been shown that this factor induces TGF-β production, and that, at the same time, hypoxia stabilizes HIF-1α, mainly by promoting EMT and related cancer metastasis [70]: ROS are not only produced by an aberrant function of mitochondrial complex III during hypoxic stress, but ROS are also stabilized by HIF-1α, thus interacting with Snail during EMT [55], in order to enhance the invasiveness in cancer cells [71] (Figure 1).