TLR4 and cancer: It has been reported that toll-like receptor (TLR) 4, which plays an important role in glial activation in neuropathic pain increased in the spinal expression of a rat model of cancer-induced bone pain and intrathecal injection of TLR4 siRNA or TLR4 signaling pathway blockers led to a pain relieving effect at an early stage, but not at day 16 of cancer-induced bone pain [15].