Figure 6

(A) The rate of DNA synthesis after UVC treatment in Fhit +/+ and −/− cells. DNA synthesis was examined at 1.5 and 6 h after various doses of UVC treatment in Fhit +/+ and −/− cells. The cells pre-labelled with ¹⁴C[TdR] were changed with pre-warmed medium before UVC. At 1 and 5.5 h after exposure to different doses of UV, 0.5 μ M ³H[TdR] was added to the cell culture. After 30 min, the cells were collected and loaded on GF-A filtres set in a Millipore Vacuum chamber. The rate of DNA synthesis for each sample was calculated as ³H/¹⁴C d.p.m. and is presented as a percentage of the control values obtained from untreated cells at the same time point. The data are presented as mean values and standard deviations from three independent experiments. (B) The CHK1 pathway is activated in UVC-treated Fhit-positive and -negative cells. The Fhit +/+ and −/− cells were treated with UV (15 J m⁻²) or untreated and harvested 2 h post treatment. Equal amounts of whole-cell extract were immunoblotted with antibodies against Chk1, phospho-Chk1 and Cdc25A, respectively. GAPDH antibody was used as the internal control for equal loading. Similar results were obtained from two independent experiments.