Fig. 5. Increased sensitivity of TLS^–/– cells and animals to ionizing irradiation. (A) Day 7 counts of MEFs with the TLS genotypes indicated. The cells were irradiated at day zero with the indicated dose of γ–rays. The number of cells on the plate at day 7 is expressed as a fraction of the cell count on an identical plate at 24 h after plating. Shown are means and SEM of a representative experiment, performed in triplicate and reproduced three times using different pools of MEFs. (B) Survival curve of a cohort of mice discordant for TLS genotype that had received 700 cGR of γ–rays on day 1. Each of the 20 TLS^–/– mice was matched with one or more siblings of TLS^+/+ or TLS^+/– genotype.