TCOF1 and ductal breast carcinoma in situ: To determine experimentally whether super-enhancer drives TCOF1 expression, we first performed luciferase reporter assays for the e1 region and showed that the e1 enhancer had significant activities in basal-like HCC1806 and MCF-10-DCIS lines (Fig. 5d), confirming it as a potent regulatory element in the super-enhancer of TCOF1.