FIGURE 7.

Cytoplasmic mutant of Chk1 does not support the cell essential function of Chk1. A, asynchronously growing WT or heterozygous HCT116 cell lines were treated with the proteasome inhibitor MG132 (2 μm) for 12 h or with 2 mm HU for 2 h and immunoblotted with the indicated antibodies. WT or heterozygous HCT116 cell lines were treated or not with indicated doses of UV light, HU, or CPT for 2 h; reseeded at a density of 1000 viable cells/6-well plate; and cultured for 2 weeks. The cells were fixed and stained with crystal violet and destained, and the absorbance was measured at a wavelength of 594 nm. The results for UV light, HU, and CPT are shown in B–D, respectively. Data represent the mean ± S.D. from three wells. The non-treated groups (0 dose) in the WT and heterozygous cell lines were set to 1.