Fig. 2.

Tumour cell viability after treatment with ionizing radiation. (A) Independently derived TERT-positive (Vec-1, Vec-2) or TERT-excised lines (Cre-4, Cre-1) (as in Fig. 1A) were subjected to 0–10 Gy ionizing radiation and analyzed for clonogenic survival (see Section 2 for details). (B) A third representative experiment with a TERT-positive (Vec-2) or a TERT-excised line (Cre-1). PDL are indicated in red; average telomere length in blue; n.d. not determined. p-Values (^**p < 0.01, ^***p < 0.0001) are relative to the earliest PDL at the same irradiation dosage. y-Axis, log₁₀ of the survival fraction; x-axis, dosage of irradiation in Gy. Error bars indicate standard deviation. (C) Plot of survival fraction (SF) as a function of average telomere length, using the data in panel (A) (upper 2 graphs), and (D), plot of the survival fraction (SF) as a function of average telomere length, using the data shown in panel (B), to demonstrate that the maximal SF occurred across a similar range of telomere lengths in independent experimental series.