Fig. 2.

Mouse morphogenes and physiogenes are significantly different in (A) the proportion of essential genes, (B) pleiotropy, and (C) tissue specificity in expression, but not in (D) the number of protein–protein interaction partners. The numbers in A indicate the number of genes. For B–D, the values of upper quartile, median, and lower quartile are indicated in each box, whereas the bars outside the box indicate semiquartile ranges. P values are from a χ² test for A (P < E-27) and from a Mann–Whitney U test for B–D. Morpho, morphogenes; noness, nonessential; physio, physiogenes.