Heibe-Kains et al. reported that mRNA expression predicts classification into four molecular subtypes by quantitative measurement of three genes on an array-based meta-analysis (ESR1, ERBB2 and AURKA) in a large study of breast cancer patients (n = 5715), which identified the major breast cancer intrinsic subtypes and provided robust discrimination for clinical use in a manner very similar to a 50-gene subtype predictor (PAM50) [30]. The gene discussed is ERBB2; the disease is breast cancer.