Figure 3: Calpain expression and activity. (a) The expressions of calpain-1, calpain-2, and the 145 kDa stable breakdown products of spectrin α-II were detected with Western blot. (b) Relative density of calpain-1, calpain-2, and stable breakdown products compared with β-actin. Data are shown as the fold changes over the control group. n = 4 for each group. (c) Calpain activity measured using a fluorescence substrate N-succinyl-LLVY-AMC. Data are shown as the fold changes over the control group. n = 3 for each group. Statistical analyses were conducted using one-way analysis of variance followed by the Tukey test. *P < 0.05, compared with control group. #P < 0.05, compared with DM group. DM: diabetes mellitus.