Figure 2.—

The log₂ fold change, between Treatment₁ and Treatment₂, of the normalized gene expression is plotted on the y-axis, and the mean log₂ expression is plotted on the x-axis. Gene expression counts were normalized by the column totals of the corresponding 2 × 2 table (e.g., Table 1). Blue dots represent significantly differentially expressed genes as established by Fisher's exact test; gray dots represent genes with similar expression. The red horizontal line at zero provides a visual check for symmetry.