Figure 2.

Association between the endogenous CUL-1 and p19^SKP1, p45^SKP2, cyclin A, and CDK2. (A) Presence of CUL-1 in the p19^SKP1, p45^SKP2, cyclin A, and CDK2 complexes. The p19^SKP1, p45^SKP2, CUL-1, cyclin A, and CDK2 complexes were immunoprecipitated from lysates prepared from actively growing HCT116 (Upper) or 293 (Lower) cells by specific antibodies as indicated on the top of each lane, respectively. The presence of CUL-1 is detected by immunoblotting with a CUL-1 specific antibody. The preimmune serum is the same as described in Fig. 1. (B) Presence of p45^SKP2 and p19^SKP1 in CUL-1 complexes. The CUL-1, p45^SKP2, or p19^SKP1 complex was immunoprecipitated from HCT116 cell lysates and immunoblotted with either p45^SKP2 (Upper) or p19^SKP1 (Lower) specific antibodies. NRS, normal rabbit serum from an unrelated rabbit.