The ranked gene contribution plots for the brain (A), muscles (B), and liver (C) gene groups. The insets show the inflection point of each curve, which defines the whole set of genes composing the signature. The changes are very sharp as the highest-ranking genes are approached, which allows the definition of a subset of genes contributing the most to the signature. The cut-off values were determined by identifying the point of maximum curvature in these regions. Panel (D) shows the change in curvature for the steepest region of each curve represented in panels (A)-(C).