There are four argounatue (AGO) proteins in humans AGO1–4 and evaluation of alterations in AGO1–4 gene expression across breast cancer cell lines and tumor samples has shown that AGO2 is increased in ER− samples versus ER+ while there is no change in AGO1, AGO3, or AGO4 [51]. This evidence concerns the gene FBXW7 and breast carcinoma.