Statistical analysis: Mean ± standard deviation was usedto show the measurement data. SPSS 19.0 (SPSS, Chicago, IL, USA) and GraphPad Prism 5.0 (Graph Pad Software, La Jolla, CA, USA) were used for graphical statistics and analysis. ANOVA was used for the statistical significance in multiple group comparisons and Student’s ttest to compare the difference between the two groups. Allassays were performed at least triplicate. P < 0.05 wasconsidered to have statistical significance.