BV induced ERK phosphorylation only in neurons that did not co-express p-p38 in the rat L4/5 spinal dorsal horn. (A-C) Double immunofluorescence in spinal dorsal horn sections (16 μm) for p-ERK (green) and NeuN, a neuronal marker (red). Double immunofluorescence indicated significant colocalization between p-ERK and NeuN. (D-F) Double immunofluorescence in the dorsal horn of an L4/L5 spinal cord section (16 μm) for p-ERK (green) and p-p38 (red). Double immunofluorescence indicated p-ERK and p-p38 did not colocalize. Scale bars, 50 μm (A-F).