Honokiol activates calpain activity.

<p>Calpain activity was measured with the fluorescent calpain substrate Suc-LLVY-AMC in N87, AGS, MKN45 and SCM-1 cells. (A) Time course responses to honokiol (20 µM) treatment. Data are expressed in terms of fold of control conditions. (B) Honokiol (20 and 40 µM) increases calpain activity at 60 min treatment. (C) Calpain inhibitors ALLN, ALLM, and Z-Leu-Leu-CHO; 25 and 50 µM) significantly inhibited honokiol-increased calpain activity. Data are presented as mean±SEM (n = 4).