Fig. 5.

Phosphorylation of Chk1 S345 during unperturbed mitosis. (A) Asynchronous H1299 lung carcinoma cells were stained with a DNA stain (DAPI) and antibodies specific for active CDK1, Cyclin B, and Chk1 phosphorylated on S345 (Chk1S345-P), as indicated. (B) H1299 cells were stained for Chk1S345-P and the centrosomal protein γ-tubulin. Shown are representative images from various phases of the cell cycle, as determined by nuclear morphology. Chk1S345-P foci are indicated (arrows). (C) Colocalizing foci of γ-tubulin and Chk1S345-P (arrows) are shown during prophase in monoallelic DLD-Chk1^WT and DLD-Chk1^S317A cells.