Validation of comprehensive transcriptomes of mouse beta and alpha cells. Bitransgenic offspring of mIns1-H2b-mCherry x S100b-eGFP bitransgenic reporter mice (A) enable the FACS purification of pure populations of beta and alpha cells (B). Expression of eGFP is negligible in mCherry + beta cells (C), and mCherry expression in eGFP + alpha cells is not detected (D). A volcano plot highlights key alpha and beta cell-enriched genes (E). The most abundantly expressed genes in beta (F) and alpha (G) cells are expressed by the fraction of total reads that maps to each gene and compared to expression in the opposite cell type. Expression of the beta cell markers Ins1 (H), Ins2 (I), Ucn3 (J) and Mafa (K) in alpha cells measures on average less than 2.39% of expression in beta cells. Conversely, expression of the alpha cell markers Gcg (L), Arx (M), Irx1 (N) and Mafb (O) in mouse beta cells is on average even lower. See also Additional files 1, 2 and 3.