Figure 1. Treatment of HeLa cells with UV stimulates phosphorylation of Chk2 at Thr68, detected by the PathScan ® Phospho-Chk2 (Thr68) Sandwich ELISA Kit #7037, but does not affect the levels of total Chk2 detected by PathScan ® Total Chk2 Sandwich ELISA Kit #7045. HeLa cells (80-90% confluent) were treated with 100 mJ/cm2 UV with 1 hour recovery at 37º C. The absorbance readings at 450 nm are shown in the top figure, while the corresponding western blots using Chk2 (1C12) Mouse mAb #3440 (left panel) or Phospho-Chk2 (Thr68) (C13C1) Rabbit mAb #2197 (right panel) are shown in the bottom figure.