We confirmed the microarray data by qRT-PCR (Fig. 1C), which revealed that MYCN overexpression in non-MYCN-amplified neuroblastoma SK-N-AS and SHEP1 cells significantly increased mRNA expression of genes encoding enzymes responsible for de novo synthesis of purine (PPAT, PFAS, PAICS, and ATIC, see also Fig. S1C) and pyrimidine (CAD, DHODH, and UMPS) nucleotides. The gene discussed is PFAS; the disease is neuroblastoma.