Figure 4.

Defective cdc2-associated histone H1 kinase activity in D8 T cells. Resting T cells were grown for 16 h in medium containing IL-2 (20 units/ml) and IL-4 (100 units/ml) lymphokines in the presence (lanes 2 and 4) or absence (lanes 1 and 3) of nocodazole (100 ng/ml). Cell lysates were prepared in Nonidet P-40 lysis buffer, and equal protein amounts (≈500 μg per sample) were immunoprecipitated with antiserum specific to cdc2. Immune complexes were used in a kinase reaction in the presence of histone H1 as the substrate. The results are representative of three independent experiments.