ARID1A and cancer: For instance, depletion of ARID1A leads to a reduction in the open histone mark (H3K27ac) at the gene enhancer regions, which in turn transcriptionally downregulates several cancer genes, such as PIK3IP1 [13], SLC7A11 [14], CDKN1A, TGF-β receptor [15], and SMAD3 [16].