Furthermore, in primary breast cancer cell lines, metformin presents an inhibitory effect on tumor invasion and metastasis due to the dual suppression of NF-kB activity and nuclear translocation mediated by MMP-9 downregulation [119], and in prostate cancer models, metformin appeared to attenuate metastasis by repressing NF-Kb signaling, thus leading to the suppression of tumor necrosis factor-α-induced EMT [120]. This evidence concerns the gene NFKB1 and breast cancer.