Rolipram and forskolin induce DNA fragmentation in CLL cells. Soluble DNA was isolated from 10 million CLL cells cultured for 72 hours in media (CT), 10 μmol/L rolipram (Roli), 40 μmol/L forskolin (Fsk) or a combination of the latter two agents (Ro/Fs). DNA fragments were resolved by electrophoresis on a 1.5% agarose gel and visualized with ethidium bromide. These data are representative of the four leukemic cell samples tested.