the effects of methotrexate ( mtx ) , fluorodeoxyuridine ( fudr ) , and hydroxyurea upon cell growth , dna synthesis , thymidylate synthase activity , and dihydrofolate reductase ( dhfr ) activity were compared in normal human epidermal keratinocytes ( nhek ) , newborn epidermal cells ( nec ) , human squamous cell carcinoma ( scc-25 ) , and a methotrexate-resistant human squamous cell carcinoma ( scc-15r ) .
C0020402
cell growth
C0007137
squamous cell