Figure 4.

Effect of ATR inhibition on CHK1 activation. HPV-negative (SQD9, CAL27, and SCC61) and HPV-positive (SCC154, SCC104, and SCC47) HNSCC cells were treated with DMSO or AZD6738 (0.5 µM) 2 h before RT. At the indicated time points, total cell lysates were prepared to perform western blotting for CHK1 ser345 (51 kDa), CHK1 (51 kDa), and vinculin (97 kDa). Densitometry quantification was performed and relative expression levels were corrected to the loading control (vinculin). kDa = molecular weight as determined by the protein standard.