XIST and breast cancer: Enumeration of ALDH+ BCSCs by ALDEFLOUR assay in MCF7 (Fig. 1L), HCC70 (Fig. 1M) and SUM159 (Fig. 1N) BCCs revealed that DOX-induced XIST KD significantly decreases the proportion of ALDH+ E-CSCs in each cell line, suggesting that lncRNA XIST is required to maintain proliferative ALDH+ E-CSCs in luminal and TN BC.