ABCB1 and breast carcinoma: In addition, reduced tumor proliferation in HMGCR-expressing tumors prior to treatment suggested that HMGCR may be predictive of the statin response (45).We therefore hypothesized that both tumor-specific HMGCR expression and the germline ABCB1 C3435T polymorphism may impact the effects of statins with regard to breast cancer prognosis.