A TRF1 -LT-Cre Wildtype-LT-Cre 53BP1 + Tel Martinez_5435_Supplementary Fig 1A- 0 20 40 60 80 100 NT ATMi (KU55933) caffeine 53BP1 positive cells (%) n=2 MEF 189 cells n=2 MEF 246 cells n=2 MEF 179 cells n=2 MEF 195 cells n=2 MEF 156 cells n=2 MEF 226 cells TRF1 -LT-Cre Wildtype-LT-Cre p<0.0001 p<0.0001 p=0.1 p=0.04 p=0.07 TRF1 -LT-Cre Wildtype-LT-Cre 0 20 40 60 80 100 Cells with > 4 TIFs (%) n=2 MEF 13 cells n=2 MEF 21 cells n=2 MEF 17 cells ATMi (KU55933) NT NT caffeine n=2 MEF 15 cells p<0.0001 p<0.0001 B C