Although we did not investigate whether c-Myc, E2F1, or MMP-9 were inhibited by SET knockdown in breast cancer cells in this study, we observed that treatment with siSET-1 and siSET-2 significantly reduced phosphorylation of Akt in MCF-7 cells (data not shown), suggesting the involvement of the Akt signalling pathway. Here, E2F1 is linked to breast cancer.