Comparison of the mouse and human beta cell transcriptomes. The unbiased comparison of mouse and human transcriptomes reveals a common core of over 9900 genes that are expressed at an RPKM value > 1 in beta cells of both species (A). A total of 725 genes (569 unique and 156 enriched) was robustly (>10-fold) and significantly (p < 1 × 10-7) higher expressed in mouse beta cells (B, red) while 815 genes (666 unique and 149 enriched) were by the same criteria significantly higher expressed in human beta cells (B, blue). Genes enriched in mouse beta cells were co-enriched for mouse-specific PDX1 binding and vice versa (C). Moreover, enrichment of PDX1 ChIP-Seq peaks in either species is associated with species-specific PDX1 binding motifs (D), as illustrated for Sytl4 (E). Iapp transcript levels in purified beta cells (F) and islet IAPP peptide content (G) are markedly reduced in human compared to mouse. Additional browser plots demonstrate notable examples of significantly enriched or selectively expressed genes in either species including Gad2 (H), Prlr (I), Ghr (J) and Cntfr (K). Human RNA-seq data are from , ChIP-Seq data are from [38, 49]. See also Additional files 8, 9 and 10.