TLR4 and breast cancer: The present study demonstrated for the first time that LPS could increase the MTDH expression via activating the TLR4-NF-κB signaling pathway in human breast cancer cells, we hypothesized that there might be a positive feedback loop that LPS stimulation initiated a signaling cascade leading to upregulated expression of MTDH, which subsequently activated NF-κB, resulting in a second phase of TLR4 activation or TRIF activation, reinforcing and amplifying LPS-induced signaling.