TABLE 1.

Correlation of transcriptional properties among orthologs

	Human	Mouse	Rat	Fly	Plant	Yeast
Human		0.460	0.428	0.213	0.246	0.165
Mouse	0.469		0.454	0.240	0.263	0.190
Rat	0.443	0.507		0.256	0.258	0.237
Fly	0.352	0.380	0.404		0.193	0.164
Plant	0.318	0.395	0.387	0.418		0.248
Yeast	0.385	0.446	0.467	0.511	0.511

For 31,046 HomoloGene entries whose expression pattern was observed in one or more species, the specieswise correlations of transcriptional activity (below the diagonal) and transcriptional variability (above the diagonal) were computed. To rule out the effect of sample-size bias, we randomly selected 20 data sets for human, mouse, and rat. However, the use of the selected data did not show differences from that of the whole data, underscoring that our measures reflect inherent biological features without regard to sample size. Spearman's rank correlation coefficient was used.