NDRG1 and breast cancer: Luminal BC patients with high NDRG1 expression had a poorer OS than BC patients with low NDRG1 expression (Fig. S4C) and, indeed, multivariate Cox-Hazard regression analysis confirmed that NDRG1 expression is a prognostic independent factor (HR: 0.58; 95% CI 0.35–0.99; p = 0.04) (Fig. S4D).