Hlaváč et al. conducted transcript level analysis of 49 human ABC transporters and immunoblotting for protein expression on post-treatment tumor and non-neoplastic tissue samples from 68 breast carcinoma patients, along with an independent series of 100 pretreatment patients, revealing downregulation of ABCC8 in breast carcinoma [59]. This evidence concerns the gene ABCG2 and breast carcinoma.