The number of p-ERK-positive neurons in SR-KO mice significantly increased after the formalin test.

<p>(A, B) Immunohistochemical analysis indicates that formalin injected into the left hind paw induced p-ERK signals (magenta) at the surface of the ipsilateral dorsal horn of the WT and SR-KO mice. Dotted lines in A and B are the outline of the gray matter of the spinal cord. The bar indicates 75 µm. (C) The number of p-ERK-positive neurons in laminae I–II significantly increased in the SR-KO mice. Values are the means ± SEM. Data are analyzed by the unpaired t-test; ** <i>p</i><0.01 (n = 5 for WT and SR-KO mice).