ERBB2 and breast cancer: The overexpression of RSK2 predicts a favorable prognostic value of RFS (Figure 8) in all those subtypes of breast cancer (luminal A breast cancer: HR = 0.78, 95% CI: 0.65–0.92, log rank p = 0.004; luminal B breast cancer: HR = 0.68, 95% CI: 0.56–0.82, log rank p < 0.001; basal-like breast cancer: HR = 0.67, 95% CI: 0.52–0.87, log rank p = 0.002; HER2+ breast cancer: HR = 0.51, 95% CI: 0.35–0.76, log rank p < 0.001).