Considering functional overlap between Hsp90 and TRAP1 in the regulation of PTP in cancer cells [7,55], the lack of functional compensation by the mitochondrial Hsp90 is quite unexpected, and may suggest different protein interaction networks between Hsp90 and TRAP1, or alternatively, that TRAP1 functionally dominates over Hsp90 in cancer mitochondria. This evidence concerns the gene TRAP1 and cancer.