(A) Representative blots of phosphorylation and total levels of PLN, RyR2, TnI and MyBP-C in WT and Hsp20 TG hearts. (B) Quantitative results of phosphorylated Ca regulatory proteins. Immunoblots revealed that pSer16-PLN/PLN and pThr17-PLN/PLN were significantly increased in TGs compared with wild types, but the phosphorylation levels of Ser2809-RYR2, Ser2815-RyR2, Ser23/24-TnI and Ser282-MyBP-C were not different between WTs and TGs. n=6 for each protein. Values = mean ± SEM. *: P<0.01. (C) Initial rates of oxalate-supported SR Ca-uptake in hearts from WT (▲) and Hsp20 TG (■) mice. There was no difference in the maximal SR Ca- uptake rates, but the EC50 value significantly decreased (inset) in TG hearts, compared to WTs. n= 5 for each group; experiments were performed in duplicates. Values = mean ± SEM, #: P < 0.05.