Distribution of corCor between human and mouse ortholog genes. X-axis is corCor value; Y-axis is number of orthologs. (a) Randomized negative control. (b) corCor between human genes and their mouse orthologs in all samples. (c) Positive control with corCor between human genes measured in nervous system and human genes measured in muscle/heart. Please note that the values on the X-axis in (b,c) are a magnitude higher than those in (a).