T60A-β5 tg and Ntg littermate mice were subject to myocardial I/R as described in Figure 1. Crude protein extracts from the indicated zones of the LV were used for western blot analyses of endogenous β5 and tg T60A-β5 (A, B) or for proteasomal chymotrypsin-like (C) and caspase-like (D) activity assays. A and B, Representative images (A) and a summary of densitometric data (B) of the western blot analyses for the endogenous β5 expressions. n=4. C and D, Changes in the indicated proteasomal peptidase activities. n=6. *p< 0.05, **p<0.01, ***p<0.005 vs. Ntg sham; #p< 0.05, ##p<0.01.