Figure 2.

Blocked DNA replication leads to a dysfunctional p53 response. (A) Exponentially growing RKO cells were γ-irradiated (10 Gy) or treated with HU (1.5 mM). Cells were lysed at the indicated time points, and total cell extracts were analyzed by Western blotting using the indicated antibodies. (B) RKO cells were treated as in A, and RNA samples were collected at the indicated time points. Northern blots were performed by using the indicated ³²P-labeled plasmid probes. The glyceraldehyde-3-phosphate dehydrogenase (GAPDH) plasmid probe was used as normalizing control. (C) RKO cells were γ-irradiated (10 Gy) or treated with HU (1.5 mM) and fixed 24 h after treatment. Immunofluorescence staining was performed by using PAb 1801 (Upper). Cells were costained with 4′,6-diamidino-2-phenylindole (DAPI) to localize the nucleus (Lower). NT, not treated.