DHFR and colorectal carcinoma: Increased expression of folate-dependent one-carbon metabolic enzymes, including, folate receptor-1 (FOLR1), dihydrofolate reductase (DHFR), serine hydroxymethyltransferase 1 (SHMT1), serine hydroxymethyltransferase 2 (SHMT2) and methylenetetrahydrofolate reductase (MTHFR) was observed in CRC cells compared to untransformed cells [50].