FIG. 6.

Phosphorylation of FL62 by immunoprecipitated CDK1/cyclin B. (A) Extracts were prepared from untreated asynchronous KB-3 cells (control), untreated synchronized cells harvested 10 h after release (mitotic), and asynchronous cells treated with 30 nM vinblastine for 16 h (VBL). Cyclin B1 was immunoprecipitated, and after a wash, the immunoprecipitates were subjected to FL62 or H1 histone kinase assays, as described in Materials and Methods. Data are means ± standard deviations (n = 3), with blank (no-substrate) values subtracted; P values are shown. (B) Whole-cell extracts (WCE) and immunoprecipitates were immunoblotted for CDK1. CON, control.