Differential expression signature similarity matrix. In the upper-right triangle region, dark red colors indicate high similarity between signatures associated with two contrasts (indicated by row and column labels). This similarity is defined by Equation (1) in the Methods section. The binary coding in the lower-left triangle region indicates whether signatures associated with two contrasts exhibit a significant level of similarity. The statistical procedure used to evaluate similarity is described in the Methods section. Contrast pairs with significant similarity (P < 0.05) are coded dark red, while pairs with non-significant similarity have no coloring.