Figure 4.

PrimPol^−/− cells are more resistant to Chk1 inhibition than WT cells. (A) Cell viability was measured using Cell Titer Blue, 48 hrs after 4 J/m² UV-C damage, where cells were maintained in 100 nM UCN-01. (B) Colony formation was analyzed in the presence of 2 mM caffeine after increasing doses of UV-C damage in comparison with survival in the absence of the inhibitor. (C) Cell Titer Blue was used to measure cell viability 48 hrs after 4 J/m² UV-C damage, where cells were pre-treated and maintained in 2.5 µM of SB203580, p38 inhibitor. Error bars represent standard deviation of independent repeats and significance was analysed using a students T-test (*p < 0.05, **p < 0.01).