ABSTRACT
Relative resistance to cytotoxic therapies, existing prior to therapy or acquired over the course of therapy, is a major clinical problem (1-3). Preclinical models of various types have been applied to the elucidation of the mechanisms of resistance to therapy and have been used to develop clinically relevant approaches to overcoming such resistance (4--6). Breast cancer, among the major solid tumors, is an example of a malignancy where resistance to cytotoxic therapies such as the antitumor alkylating agents can develop (7,8).
