2.13. Statistical analysis
All data were expressed as mean ± standard deviation (SD) of at least three independent experiments. Statistical analyses were performed using GraphPad Prism 6 software (GraphPad Software Inc., La Jolla, CA, USA). Differences among more than two groups were analyzed by one-way ANOVA followed by a Tukey HSD comparison test. Values of P < 0.05 were considered statistically significant.