Introduction of the same alleles into BIBR-treated HTC75 cells at PD245 by lentiviral infection (Supplementary Fig. 5f) showed that overexpression of TRF1.WT, but not Vector or TRF1.AA, led to an increase in RAD51 foci (Supplementary Fig. 5g, h) and DNA damage foci (Supplementary Fig. 5i, j), similar to results described above for normal aged cells and ALT cancer cells. Here, TERF1 is linked to cancer.