CFA-induced mechanical allodynia is reduced in mice lacking JNK1. CFA produced rapid and persistent bilateral mechanical allodynia (A, B) and ipsilateral heat hyperalgesia (C, D) in wild-type mice. But in JNK1−/− mice, mechanical allodynia is attenuated bilaterally, especially in the maintenance phase (A, B). CFA-induced heat hyperalgeisa is comparable in wild-type and JNK1−/− mice (C, D). *, P<0.05; **, P<0.01; compared to wild type mice at the corresponding time points. Notice that the baseline pain sensitivity is normal in the knockout mice. n = 7–8.