ERBB2 and breast cancer: CTTN overexpression was associated with poorer survival outcomes in HER2+ breast cancer patients in METABRIC (OS, p = 0.008; DFS, p = 0.010; Figure 1E, top), our cohorts (OS, p = 0.05; Figure 1F), and Kaplan–Meier plotter (OS, p = 0.0014), and it showed a tendency toward shorter relapse-free survival (RFS) in Kaplan–Meier plotter (p = 0.066; Figure 1E, bottom).