Fig. 5: Chk1 directly phosphorylates Plk1 to disturb its interaction with Sgo1.

A–C After transfection of plasmids and B[a]P treatment, the localization of myc-Plk1 and multipolar spindles was analyzed (n = 300). D, E Chemically treated HeLa cells were analyzed by immunoblotting. F Cells were treated with the indicated inhibitors and B[a]P and analyzed by immunoblotting. G, H WT or mutant His-Plk1 was incubated with active Chk1 and analyzed by immunoblotting. I Recombinant Chk1 was incubated with recombinant His-Plk1 and proteins pulled down with Ni-beads were analyzed by immunoblotting. J After treatment with 0.5 µM B[a]P for 48 h or 300 ng/ml nocodazole for 16 h, cells were treated with 1 µM RO3306 as a Cdk1 inhibitor for 5 h, 1 µM BI2536 as a Plk1 inhibitor for 1 h, 5 µM VX680 as an Aurora A inhibitor for 1 h, and 2 µM Hesperadin as an Aurora B inhibitor for 5 h. Cell lysates were analyzed by immunoblotting. K His-Plk1 was incubated with Aurora A, pulled down with Ni⁺-beads, and analyzed by immunoblotting. L Lysates from DNA-transfected HeLa cells were incubated with recombinant His-Sgo1 and proteins pulled down with Ni-beads were analyzed by immunoblotting. Images of uncropped blots and gels are provided as a Supplementary Material file. Scale bar, 5 µm. Error bars, SEM. ^*p < 0.01 (two-tailed t test).