Statistical analysis.
Data are presented as median with interquartile ranges or mean with SEM. The non-parametric Mann-Whitney test was used to compare unpaired values (GraphPad Prism®). Values of p<0.05 were considered significant. The level of significance is indicated with asterisks: *, p<0.05; **, p<0.01; ***, p<0.001; ****, p<0.0001 and n.s., non-significant.