To investigate Ago2 expression in breast cancer, cell lines representing the four common molecular subtypes: T47D (Luminal A), BT-474 (Luminal B), SK-BR-3 (HER2 positive), BT-20 (Basal/Triple negative), and one non-cancer non-tumourigenic control breast epithelial cell line (MCF-10A) were profiled. This evidence concerns the gene ERBB2 and cancer.