MTHFD2 is a mitochondrial enzyme that catalyzes key reactions in one-carbon metabolism, specifically methylenetetrahydrofolate dehydrogenase and methenyltetrahydrofolate cyclohydrolase activities 1. The enzyme primarily supports de novo purine synthesis by generating one-carbon units within mitochondria, which are essential for nucleotide biosynthesis 2. MTHFD2 also contributes to mitochondrial tRNA methylation, specifically producing taurinomethyluridine modifications required for proper mitochondrial translation and oxidative phosphorylation 3. Beyond its metabolic functions, MTHFD2 exhibits non-metabolic roles in cell signaling by driving UDP-GlcNAc biosynthesis, which promotes O-GlcNAcylation of proteins including cMYC, enhancing transcription factor stability and PD-L1 expression 4. MTHFD2 is highly upregulated in various cancers and serves as a metabolic checkpoint controlling T cell differentiation and inflammatory responses 5. The enzyme is regulated by mTORC1 signaling through ATF4 transcription factor activation 2. Clinically, MTHFD2 represents a promising therapeutic target, as its inhibition shows anticancer effects and can overcome drug resistance mechanisms, including sunitinib resistance in renal cell carcinoma 67.