Through pattern recognition analysis and single variable analysis, in total 12 differentially expressed metabolites in B16 cells were identified upon radiation, including 4 content increased metabolites (alanine, glutamate, choline, and glycine) and 8 content-decreased metabolites (leucine, lactate, acetate, creatine, creatine phosphate, methanol, UDP-glucose and ATP). Correspondingly, for those content-changeable metabolites, their KEGG IDs and changes were listed in Table 2.