BRG1, also known as SMARCA4, is a protein that serves as the essential ATPase subunit of the SWI/SNF chromatin-remodeling complex. This complex plays a crucial role in regulating gene expression by altering the structure of chromatin, which in turn affects the accessibility of DNA to the transcription machinery. BRG1 functions by maintaining chromatin accessibility at gene transcription start sites (TSSs) and enhancers, which is vital for the binding of transcriptional coactivators like p300 and the subsequent acetylation of histones, such as H3K27. BRG1 has also been implicated in cancer development. In B-cell acute lymphoblastic leukemia (B-ALL), BRG1 overexpression is associated with worse outcomes and promotes the proliferation and survival of leukemia cells. The inhibition of BRG1 leads to cell cycle arrest and increased apoptosis in B-ALL cells, suggesting that BRG1 may be a potential therapeutic target for this type of cancer.