DICER1 and ductal breast carcinoma in situ: By comprehensively studying the miRNA levels across the entire spectrum of breast cancer progression, our results specifically suggest that there is a global upregulation in DICER and mature miRNAs from untransformed cells to preneoplastic cells (MCF10.AT1) that stays high through DCIS, and that there is an eventual global downregulation of DICER and miRNAs in invasive cancer (MCF10.CA1D) compared to atypia.