ABCG2 and breast cancer: Yamada et al[34] conducted a study using a tissue microarray with 281 breast cancer patient samples (17 luminal A, 27 human epidermal growth factor receptor 2 [HER2], 46 triple-negative, and 191 luminal A breast cancer) to investigate the expression levels of various ABC transporters; the expression levels of ABCC1 and ABCC11 were found to be associated with a substantially shorter disease-free survival.