Abstract

Mutations in DNA topoisomerase II are often correlated with drug‐resistance in tumor cell lines. Studies of topoisomerase II‐mediated drug‐resistance in various model systems, as well as the sequencing of such mutations from drug‐resistant tumors, have shed light on the functional domains of topoisomerase II, on how it interacts with inhibitors, and on the different mechanisms by which cells avoid the toxic effects of many clinically important anti‐tumor drugs.