Differential “metabogram” plotted according to correlation coefficient and VIP value. A: Radiated and untreated B16 cells were distinguished in principal component score chart, which indicated that the metabolic profiling of radiated B16 cells was different with that of untreated cells, t and t are scores on PC1 and PC2, respectively. B: Score chart of partial least squares discriminant analysis model distinguished radiated B16 cells and untreated B16 cells. C: 400 cross validations indicated little over-fitting and a reliable model. D:OPLS-DA model distinguished radiated and untreated B16 cells. E: Differential metabolites were distinguished in radiated and untreated cells according to VIP, relevant index r and loading value.