MTHFD1L and breast cancer: The authors further suggest that 5’-tRFCys targets metabolic transcripts, such as platelet-activating factor acetylhydrolase 1 beta 1 (Pafah1b1), which promotes BC cell metastasis via regulating phosphatidylcholine synthesis, and methylenetetrahydrofolate dehydrogenase 1-like (Mthfd1l), a key metabolic enzyme in the folate cycle that affects the production of metabolites (mainly formate and glycine), thereby regulating metabolic pathways for BC progression, assisting BC cell metastasis and leading to poor prognosis.