Statistical analysis
Data are expressed as mean ± SEM. Statistical comparisons between experimental groups were performed using one-way ANOVA and post-hoc Tukey or Dunnett’s multiple comparison tests. For less than three experimental groups, Student’s unpaired two-tailed t -test was employed. Data were analyzed with Microsoft Excel (Microsoft, Redmond, Washington, USA) and Prism 6.0 (GraphPad Software, San Diego, California). A ‘p ’ value of less than 0.05 was considered statistically significant for all analyses.