Description of ALT lines used in this study and summary of results.

(a)CF, cystic fibrosis; HPV, human papillovirus 16 E6 and E7; LF, Li-Fraumeni syndrome; LN, Lesch-Nyhan syndrome; OS, osteosarcoma; SV40 ER, simian virus 40 early region.(b)Values are averages of triplicate assays (±SD) with JFCF-6/T.1D set to 100 in each assay and the other values expressed relative to this standard. BJ and HeLa values are below 2.(c)Bold: aberrant ATRX or DAXX protein in western and/or IF. ATRX western results are from three independent immunoblots. Examples of abnormal IF are given in Figure 1b.(d)Bold: deletions in ATRX. See Table S1 for details.(e)Values represent mean % cells with micronuclei and SDs from three independent experiments. See Figure 4. Values for HeLa and BJ/SV40 are 10% of cells with micronuclei.(f)Bold: abnormal G2/M checkpoint initiation (Figure 5A. Italic: uninterpretable due to low mitotic index. hTERT-RPE (positive control) 89% and ATM-/- GM5849 46%.(g)Bold: abnormal G2/M checkpoint maintenance (Figure 5b. Italic: low mitotic index at 16 hr in noc. Values for HeLa and BJ/SV40 were 98±2% and 96±3%, respectively.(h)Bold: slow DSB repair kinetics. See Figure 6A and Figure S8. After 0.5 Gy IR, cells with >10 53BP1 foci were scored at 1 and 24 hr and without IR. Values represent (% at 24 hr)-(% no IR)/(% at 1 hr)-(% no IR). nt: not tested.(i)Bold: abnormal residual DNA fragmentation 24 hr post IR. See Figure 6B. nt: not tested.(j)Bold: greater than 60% of cells containing >10 spontaneous 53BP1 foci.(k)A. Englezou, P. Bonnefin, R. Reddel, unpublished data.(l)J. Plowman, L. Huschtscha, R. Reddel, unpublished data.