Fig. 1.

Cardiac ER unfolded protein response (UPR^ER) proteins are induced by MI but blocked after exosome treatment. Western blots were used to determine relative abundances in cardiac aggregates of 3 proteins that are indicative of UPR^ER activity: phospho-PERK (P-PERK), GRP78, and ATF6. A Representative western blots are shown for these 3 UPR^ER proteins, adding GAPDH as an internal standard for quantitation. B Histograms show quantified lane scans, as means ± SD. Significance of differences between MI and other groups was assessed by 2-tailed heteroscedastic t tests, appropriate for small groups in which variance is unequal or unknown: *P < 0.05; **P < 0.01