As illustrated in the heatmaps, pyrimidine metabolic rate–limiting enzymes CAD, CTPS, CTPS2, DHODH, DTYMK, NT5C3, RRM1, RRM2, TK2, TYMS, UCK2, and UCKL1 were highly expressed in tumor tissues (Fig. 11). The gene discussed is DHODH; the disease is neoplasm.