The rationale of such an approach is supported by several studies performed on non-stem cancer cells: In model systems, co-treatments of tumor cell cultures with HSP90 activity inhibitors and known inhibitors of HSF1-mediated HSP induction, such as quercetin, KNK437, triptolide, and NZ28, significantly enhanced the cytotoxic and/or radiosensitizing effects thanks to prevention of HSF1-mediated HSP induction [96,97,98,99]. This evidence concerns the gene HSP90AA1 and neoplasm.