(Figure 1E) along with the trend of occasional pATM and γH2A.X activation in Figure 3C suggests that the variant of ATM expressed in Q1SA is capable of phosphorylating downstream targets in a small number of cells. However, detection of pATM and γH2A.X staining in a very small number of Q3SA cells could not be explained by the genotype of these cells, and therefore it is possible that the same type of gene reversion had occurred as that detected in Q3SC. These results indicate that the A-T iPSC are generally stable, at least over the period of this assay, but that XR-induced reversion can be detected at low frequencies in both Q1SA and Q3SA cells.
