PAICS and lung cancer: Our analysis using lung cancer gene expression profiling studies [27–33] available in the Oncomine [OncomineTM Platform (Life Technologies, Ann Arbor, MI) was used for analysis and visualization] [34], showed significantly increased expression of de novo purine biosynthetic enzymes phosphoribosyl pyrophosphate amidotransferase (PPAT), phosphoribosylaminoimidazole carboxylase, phosphoribosylaminoimidazole succinocarboxamide synthetase (PAICS) (Fig. 1A; Supplementary Fig. S1A).