SHMT1 and cancer: Thus, serine/glycine one-carbon (SGOC) metabolism and, in particular, serine hydroxymethyltransferase (SHMT), the enzyme providing activated one-carbon units by converting serine and tetrahydrofolate (H4PteGlu) to glycine and 5, 10-CH2-H4PteGlu (ME-THF), represent focal points of the metabolic reprogramming of cancer cells.