SLC7A5 and cancer: Cancer cells could directly increase the uptake of methionine through the overexpression of amino-acid transporters LAT1 and LAT4 (SLC7A5/SLC43A2).45, 46 Alternatively, overexpression of 3-phosphoglycerate dehydrogenase (PGDH) diverts glycolysis intermediates to the serine-glycine biosynthesis pathway.47, 48 Serine participates in one-carbon metabolism through donation of its side chain to tetrahydrofolate to drive the folate cycle, which in turn recycles methionine from homocysteine.