A set of microRNAs such as mir-342, mir-299, mir-217, mir-190, mir-135b and mir-218 were found to be associated with the estrogen receptor status in breast tumor samples in which a miRNA signature able to predict ER, progesterone receptor (PgR) and human epidermal receptor-2 (HER2) status was highlighted through an artificial neural network (ANN) analysis [27]. This evidence concerns the gene ESR1 and breast neoplasm.