Interestingly, Dicer mRNA expression was found to be tumour stage-dependent, with increasing levels between immortalised cells and cell lines established from ductal carcinoma in situ, and a subsequent marked decrease in cell lines established from invasive ductal carcinoma and in cell lines established from metastases (P-value <0.0001, Table 1). Here, DICER1 is linked to ductal breast carcinoma in situ.