GART (phosphoribosylglycinamide formyltransferase) is a trifunctional enzyme catalyzing three distinct reactions in the de novo purine biosynthetic pathway 1. The protein contains three enzymatic domains: phosphoribosylglycinamide synthetase (GARS), aminoimidazole ribonucleotide synthetase (AIRS), and glycinamide ribonucleotide formyltransferase (GART) activities 2. Located on chromosome 21.1, GART is expressed during human brain development and shows temporal overexpression in cerebellum of Down syndrome individuals 2. Beyond its canonical purine biosynthetic role, GART possesses a novel methyltransferase function, methylating RUVBL1 at the K7 site to enhance protein stability 3. Clinically, elevated GART expression correlates with poor prognosis in colorectal cancer and non-small cell lung cancer, promoting tumor stemness and proliferation through activation of the RUVBL1/β-catenin and PAICS-Akt-β-catenin signaling pathways, respectively 34. The gene is organized into 11 coding exons spanning approximately 40 kb, with alternative splicing generating a monofunctional 50 kDa GARS protein 12. Pemetrexed, a GART-targeting compound, shows promise as a therapeutic agent for cancer treatment 3.