BDNF-induced phospho-ERK immunohistochemical signals in DRG cultures after TNF-α treatment. Phospho-ERK signals were detected after a 5 nM TNF-α pre-treatment for 48 hours followed by 400 ng/ml BDNF for 0-40 min. Phospho-ERK and TNFR1 proteins were detected by double immunofluorescent stain. Photomicrographs illustrate the protein signals of individual phospho-ERK and TNFR1 or merged phospho-ERK/TNFR1 in control (no TNF-α pre-treatment) (A) and TNF-α groups (B). Scale bars, 50 μm.