Uptake as a determinant of methotrexate response in mouse leukemias

Methotrexate-promoted survival of mice bearing different transplantable leukemias was compared with uptake of the drug by leukemia cells in vitro. A high degree of correlation (r(2) = 0.88) showed that uptake may be a major determinant of the antitumor activity of methotrexate against transplantable mouse leukemias.