Fig. 2. Extracellular signal–regulated kinase phosphorylation (pERK) immunofluorescence in the superficial dorsal horn of spinal cord in control unstimulated (  A ), capsaicin (3 μm, 10 min)–stimulated (  B ), and capsaicin-stimulated with bupivacaine (2 mm) (  C ). Only the activated, phosphorylated form (pERK) binds the antibody.