YM155 potentiates the activation of Cdc2 kinase and suppresses protein expression related to G
/M checkpoint. A. Irradiated Eca109 cells were treated with YM155 in the absence or the presence of nocodazole. Cdc2 was immunoprecipitated using Cdc2 antibody and Cdc2 kinase activity was measured by Histone H1 kinase assay described. The relative Cdc2 kinase activity was shown in the histogram (right) (*, P < 0.05; **, P < 0.01). B. Eca109 and TE13 cells were treated with YM155, X ray or the combination modality and subjected to Western blot analysis of G2/M checkpoint related proteins phospho-Cdc2, Cdc2, cyclin B1, phospho-Cdc25C.