In this study, we examined XIST expression across a spectrum of BC cell lines representing different BC subtypes and investigated the impact of DOX-inducible KD of XIST on the maintenance of ALDH+ E- and CD24loCD44hi M-like CSCs, as well as tumor growth and tumor-initiating potential in mouse xenograft models of luminal and TN BC. Here, XIST is linked to neoplasm.