Although HIF-1α has been shown to upregulate Slug expression during EMT in head and neck squamous cell carcinoma cells43, we did not detect changes in Slug mRNA levels in lung cancer cells upon HIF-1α knockdown or exposure to hypoxia (Supplementary Fig. 10b,c), suggesting that alternative pathways are involved in hypoxia-mediated Slug upregulation at the protein level. This evidence concerns the gene SNAI2 and lung carcinoma.