HSP90AA1 and head and neck squamous cell carcinoma: Single dose exposure to radiation alone was found to cause minimal upregulation of HSP72 in vitro in HeLa cells or the two HNSCC cell lines, HN3 or HN5, with any effect of radiation in combination with NVP-AUY922 masked by predominant HSP90 inhibition-induced HSP72 upregulation (Fig. 3C, D; Fig. S2).