In the lung metastasis model of breast cancer, the combination of FB23 and ibrutinib led to a significant reduction in the protein expression levels of c-Myc and E2F1 (Fig. 6L), as well as the mRNA expression levels of c-Myc (Fig. 6M and N) in MDA-MB-231LMF3 and BT-549LMF3 cells. Here, E2F1 is linked to breast cancer.