The synthesis of what deoxyribonucleotide will be directly affected by inhibition of dhfr? explain why methotrexate treatment of cells can cause misincorporation of uracil into dna. even though methotrexate inhibits dihydrofolate reductase it has broad reaching effects on other metabolic pathways. explain why methotrexate would also inhibit purine nucleotide metabolism, methionine metabolism and potentially interfere with all reactions involving single carbon carriers in cells. why do you think low dose methotrexate treatments are used as immune system suppressants or for treatment of psoriasis, a skin disease that typically occurs by the over proliferation of skin cells?