Statistical analysis
All experiments and data analysis were blinded. The median lethal dose (LD50) was obtained through sigmoid curve fitting by plotting cell viability versus the log10 OXA concentrations. Data are presented as the means ± standard error of the mean (SEM). For thein vitro data, each point was obtained from at least two independent experiments with five or six samples each. Unpaired two-tailed Student’s t test was used to analyse differences between two groups, and one-way analysis of variance (ANOVA) followed by Bonferroni’s or Dunnett’s post hoctest was used for multiple-group comparisons. A P -value < 0.05 was considered statistically significant. All data analyses were performed using GraphPad Prism 5.0 (GraphPad Software Inc., San Diego, CA, USA).