Figure 4.

Stabilization of Cdc18^CDK by overexpression of Cdt1. S. pombe strains expressing the Cdc18^CDK alone (lane 1) or coexpressing wild-type (WT) Cdt1 and Cdc18^CDK (lanes 2, 3, and 4) or coexpressing Cdt1^S382A and Cdc18^CDK (lanes 5, 6, and 7) were derepressed for 20 h. Extracts were prepared as described previously (15) and analyzed by SDS/PAGE followed by immunoblotting with 16B12 anti-HA monoclonal antibodies (Babco, Richmond, CA) to detect Cdc18^CDK. The blot was stained with Ponceau S to confirm equal loading.