JAG1 and breast cancer: This finding, in addition to the positive association between Jagged1 and T-bet+ TILs observed in this study, suggests that in BRD4+/high, T-bet+/high tumors, BRD4-mediated upregulation of Jagged1 may reinforce the anti-tumoral activity of T-bet+ TILs, and facilitate disease-free survival of patients with breast cancer.