As illustrated in the heatmaps, pyrimidine metabolic rate–limiting enzymes CAD, CTPS, CTPS2, DHODH, DTYMK, NT5C3, RRM1, RRM2, TK2, TYMS, UCK2, and UCKL1 were upregulated in lung cancer tissues (Fig. 2). The gene discussed is UCK2; the disease is lung carcinoma.