GraphPad Prism v.6.0 software (GraphPad Software) and SAS 9.4. software (SAS Institute Inc.) were used for statistical analyses. Unpaired two-tailed t test with Welch’s correction was used for comparison of means between two groups, one-way ANOVA was used to compare means among more than two independent groups followed by Tukey’s multiple comparisons test, and two-way ANOVA with Bonferroni-corrected post hoc t tests were used to compare the mean differences among groups classified by two factors. Differences were considered statistically significant when P values were less than 0.05.