Statistical analysis
Each sample was analyzed in triplicate. Data are expressed as mean ± SEM. Student’s t-test was used for comparison between 2 means and a one-way analysis of variance (ANOVA) followed by Tukey’s test was used for comparison of more than 2 means A difference was considered statistically significant when P < 0.05. Data analyses were performed using the GraphPad Prism 5.0 software.