DHFR (Dihydrofolate Reductase) is a key enzyme involved in the cellular folate metabolism pathway, primarily responsible for reducing dihydrofolate to tetrahydrofolate, a step crucial for DNA synthesis and cell replication. DHFR is mainly located in the cytoplasm. This enzyme is expressed in all cells that require DNA synthesis and repair, with its activity tightly regulated by cellular proliferation needs. Mutations or changes in expression of the DHFR gene can lead to abnormalities in folate metabolism, affecting cell growth and differentiation, and it is also a target for certain anticancer drugs.