Fig. 2
From: Tumor hypoxia and role of hypoxia-inducible factor in oral cancer
 Causes and downstream pathway of hypoxia in HNSCC prognosis. (Modified and reproduced with permission from Kujan O, Shearston K, Farah CS. The role of hypoxia in oral cancer and potentially malignant disorders: a review. J Oral Pathol Med. 2017 Apr;46(4):246-252. doi: 10.1111/jop.12488. Epub 2016 Aug 25. PMID: 27560394