Our data demonstrate that SOX4 and SMARCA4, which are uniformly overexpressed in basal-like tumors, form a previously unreported complex that is required to mediate epigenetic reprogramming of the TGFBR2 chromatin landscape and regulate TGFBR2 expression to promote PI3K signaling in this subset of breast-cancer patients. This evidence concerns the gene SMARCA4 and breast cancer.