DHFR can be targeted in the treatment of cancer and as a potential target against bacterial infections. DHFR is responsible for the levels of tetrahydrofolate in a cell, and the inhibition of DHFR can limit the growth and proliferation of cells that are characteristic of cancer and bacterial infections. Methotrexate, a competitive inhibitor of DHFR, is one such anticancer drug that inhibits DHFR. Other drugs include trimethoprim and pyrimethamine. These three are widely used as antitumor and antimicrobial agents. Other classes of compounds that target DHFR in general, and bacterial DHFRs in particular, belong to the classes such as diaminopteridines, diaminotriazines, diaminopyrroloquinazolines, stilbenes, chalcones, deoxybenzoins, to name but a few.