PDE inhibitors suppress the growth of human CEM ALL cells in culture.

CEM cells were cultured with each drug for 4 days, and MTT assay measurements are expressed as a viability ratio of drug-treated cells to untreated control cells in each experiment. Error bars represent standard deviation ranges for each data point. Nonspecific inhibitors include aminophylline (A), enprofylline (B), dyphylline (C), pentoxyfylline (D), and caffeine (E). Specific inhibitors include PDE4-specific rolipram (F), PDE3-specific trequinsin (G), and relatively PDE1-specific vinpocetine (H). The dashed lines and open symbols depict the sensitivity profile of each drug alone on CEM cells. The solid lines and closed symbols delineate the sensitivity profile of each drug when combined with 1 μM dexamethasone.