Effect of rapamycin on PMA/CD28-induced phosphorylation status of 4EBP-1.

Peripheral blood T cells were treated with either medium alone, PMA/αCD28, or PMA/αCD28 plus pretreated rapamycin for various periods of times. Total cellular lysates (25 μg) were analyzed by immunoblotting with an antibody specific for phospho–4EBP-1 that is phosphorylated on Ser-65. Arrows indicate the different phosphorylated forms of 4EBP-1.