DHFR and non-Hodgkin lymphoma: Other promising agents for cancer are folate metabolism inhibitors, drugs that have shown efficacy on several types of cancer including NHLs; for example, methotrexate (MTX) is a widely used drug to treat NHL and is an inhibitor of the enzyme dihydrofolate reductase (DHFR), resulting in the reduction of THF and slowing down of DNA synthesis and cell proliferation [22,23].