Importantly, we discovered that the methylenetetrahydrofolate dehydrogenase 2 (MTHFD2), a key enzyme in the transformation of folate metabolites, was markedly upregulated in tumor cells from solid LUADs, along with the enhancement of folate biosynthesis and one-carbon pool by folate (Fig. 1C, Fig. 2A; Additional file 2: Table S2). The gene discussed is MTHFD2; the disease is neoplasm.