TOP2A and cancer: To test whether the link between Top2α expression level and CX-5461 resistance is cell type (cancer type)-specific, we measured a CX-5461 dose–response using the HTETOP cell line, a modified human fibrosarcoma HT1080 cell line where Top2α expression can be >99.5% ablated by treatment with doxycycline (Dox) [25] (Supplementary Figure S3A).