E2F1 and breast carcinoma: In addition through a search of the Genes-to-Systems Breast Cancer Database (http://www.itb.cnr.it/breastcancer/) we find evidence of interaction of all the 4 miRNAs with gene targets such as E2F1, E2F3, DAPK1 and others implicated to be altered in breast cancer cells (Fig. S4).