Knockdown of ARID1A in breast cancer cell lines led to widespread alterations in chromatin accessibility, SWI/SNF binding, and occupancy of the pioneer transcription factor FOXA1-ER complex, as well as transcriptional reprogramming from a luminal to a basal-like gene signature, and resistance to anti-estrogen therapies such as tamoxifen and fulvestrant, both in vitro and in xenograft models [95,99]. Here, ARID1A is linked to breast cancer.