TCF4 and breast cancer: Moreover, we detected that fibroblast growth factor receptor 4 (FGFR4) could trigger β-catenin/TCF4 signaling to induce anti-HER2 resistance in recalcitrant HER2-positive breast cancer and the utilization of a selective inhibitor of FGFR4, roblitinib, exhibited a potent antitumor effect on trastuzumab-resistant HER2-positive breast cancer cells [55].