PPAT and cancer: Many enzymes of the de novo purine biosynthesis pathway were found to have a high hazard ratio (HR) with regard to their gene expression level and overall survival in these combined cancer cohorts, with three of them—PPAT, glycinamide ribonucleotide transformylase (GART), and GMP synthase (GMPS)—being ranked in the top four (Fig. 6a).