BDNF and neuropathic pain: Microglial MAP kinases can be activated by IL-1β and TNF-α, inducing, via transcription factors such as NFκB, additional production of IL-1β, TNF-α, IL-6, IL-10, TGF-β, PGE2, BDNF, and cathepsin S and promoting the deleterious effects of microglial infiltration and phagocytosis in neuropathic pain.