In breast cancers, PP2A has been reported to be involved in progression through various important signalling pathways; indeed, it has been reported that Her-2 receptor induced PP2A phosphorylation [45] that PP2A induced ERα dephosphorylation [46] and ERα mRNA instability [47], and that PP2A induced Akt dephosphorylation [48], [49], [50]. This evidence concerns the gene ESR1 and breast cancer.