Figure 4. Distribution of effect sizes for all possible substitution mutations in three mammalian enhancers.
For the three enhancers studied (two replicate libraries for LTV1), plotted is the cumulative fraction of substitutions possessing a given effect size expressed as the absolute value of the effect size of a given substitution. For example, across the three enhancers, between ~80% and ~95% of substitutions influence transcriptional activity by less than a factor of 1.5.