Dihydrofolate reductase functions to reduce dihydrofolate to tetrahydrofolate, a vital process for cellular one-carbon metabolism and cofactor availability.
The claim states that dihydrofolate reductase functions by reducing dihydrofolate to tetrahydrofolate. Papers 6 and 11 explicitly support the biochemical function of dihydrofolate reductase (DHFR) in reducing dihydrofolate (or related pterins) to the tetrahydro form (tetrahydrofolate) to serve as a cellular cofactor. No retrieved papers refute this fundamental biochemical role.