Fig. 2

Normalized intensity levels of the spots selected for MS analysis. The relative amount of signal for each spot is expressed as a log10 normalized volume (spot optical density). Values are means ± SEM (n = 16, AL, SM; n = 12, IS). Statistical significance was evaluated by one-way ANOVA analyses, followed by Tukey HSD test (see Additional file 1: Table S1 for a summary of the test). Letters mark statistically significant treatments. Data are reported as p-values (*, 0.01 < P ≤ 0.05; **, 0.001 < P ≤ 0.01; ***, 0.0001 < P ≤ 0.001; ****, P ≤ 0.0001). AL, Alba; IS, Isernia; SM, San Miniato