Table 1

The effect of DNA replication inhibitors on entrance to mitosis in cycling extracts. Cycling extracts (27) were prepared and mixed with buffer [phosphate-buffered saline (PBS)], aphidicolin (APX) (100 μg/ml), recombinant geminin (250 nM), purified monoclonal antibody SJK-132 (1 mg/ml), or actinomycin D (Ac.D) (10 μg/ml). After 10 min on ice, the reactions were supplemented with sperm nuclei (2000/μl) and cycling was initiated by transferring the reactions to room temperature. Entrance to mitosis was taken as the time at which more than 50% of the nuclear envelopes had broken down [NEB (27)], which is indicated in minutes. For reactions where NEB did not occur during the 120-min time course of the experiment, a dash appears in the second column. The data are from a single experiment and are representative of three independent experiments.

Addition T > 50% NEB
Buffer 60  min
Geminin 55  min
Ac.D55  min