original mother population retained viability, and continued to increase as the viability of the population declined below 10%. Thus, the increase in LOH rate at MET15 affects cells that have exceeded the median life span potential of the population. In contrast, while there was a trend towards increasing LOH rates with increasing replicative age for the first 72 hours at the chromosome IV locus, it did not reach the level of significance at any age (p>0.05, Fisher's exact test using contingency tables) (Figure 1B). These results suggested that this age-associated increase in LOH was locus-specific, affecting MET15 on chromosome XII.
