[i] Mouse transcript identification (ID) listed with the number of SNPs, the number of BL6 reads, the number of spretus reads, and the ratio between BL6 (inactive X) and spretus (active X) reads. Corresponding human transcripts and human strata are listed together with their escape status expressed as the number of rodent × human hybrid cell lines that retain the human inactive X chromosome and express the gene/total number of cell lines tested (Carrel and Willard 2005; Ross et al. 2005). —, Not determined.