CIP2A and breast carcinoma: Furthermore, CIP2A is associated with radioresistance and modulates the sensitivity of breast cancer cells to bortezomib treatments.15 Choi et al.16 determined that CIP2A expression is associated with the sensitivity to doxorubicin and CIP2A overexpression in MCF-7 cells overcame the inhibition of cell proliferation in response to doxorubicin treatment.