PGP and neoplasm: To investigate if LXRα protein was associated with Pgp expression in ER-negative breast cancer patients, ABCA1 mRNA, Pgp mRNA, LXRα protein expression were measured in a cohort of ER-negative tumor samples from the Leeds Breast Research Tissue Bank (LBRTB cohort: n = 47; patient characteristics reported in Supplementary Table S1; representative immunoblots shown in Supplementary Figure S10).