Computer modeling studies of drug effects on cells in vitro are continuing. In vitro studies of two dose schedule optimization of hydroxyurea and cytosine arabinoside suggest that the optimum time for the second dose occurs when recruited cells are passing through mid-S. In vitro studies of adriamycin demonstrate proliferation dependent drug effect, without immediate suppression of DNA synthesis. Kinetic studies in Sezary's syndrome have shown that the skin is not the primary site of cell production, and that both the rate of cell production, and the rate of cell loss are high in this disease. Flow cytometry studies of the non-Hodgkin's lymphomas show that the large cell lymphomas have a high frequency of aneuploidy, and high proliferative rates in comparison with the small cell lymphomas.