Specifically, in breast cancer, various studies have identified mis-expressed miRNAs in tumours vs. normal tissue, and shown that changes in their expression seem to define, similarly to what has been found by expression profiling of coding genes, different histological (lobular/ductal, ER+/ER−) [11], [12] and molecular (luminal A, luminal B, basal-like, HER2+) subtypes described so far [13]. This evidence concerns the gene ERBB2 and breast carcinoma.