“…This approach successfully filters out highly expressed genes in contaminating cell types (e.g., SST, GCG from somatostatin, and glucagon cells contaminating the beta cell population), otherwise mistaken as key players in the expression signature of beta cells. In addition to known beta-cell-specific transcripts (INS, IGF2, PDX1) we highlight further targets, some featured already in a microarray analysis of sorted islet cells (Dorrell et al 2011b), e.g., RGS16, negative regulator of G-protein signaling, involved in endocrine pancreas development and re-expressed in adult cells in response to GLP-1 (Villasenor et al 2010); ADCYAP1, pituitary adenylate cyclase activating polypeptide 1, involved in insulin secretion and beta cell regeneration/proliferation (Sakurai et al 2011); HADH, hydroxyacyl-CoA dehydrogenase, negative regulator of insulin secretion (Hardy et al 2007) associated with Alzheimer's (Nicolls et al 2003), which is in turn associated with diabetes. Many other genes however have not been described before in the context of beta cells, including: NPTX2, neuronal pentraxin 2, found in neuronal cells and gliomas but also shown to be frequently downregulated in pancreatic cancers (Zhang et al 2012); TSPAN1, tetraspanin 1, which can associate with alpha6.beta1 integrin and promote FAK phosphorylation (Huang et al 2008) shown by us to be involved in insulin secretion (Rondas et al 2011); GPM6A, neuronal membrane glycoprotein of unknown function but identified as a beta cell marker in sorted mouse islet cells (Dorrell et al 2011a); BMP5, bone morphogenic protein 5, implicated in pancreas and fetal beta cell development ( Jiang et al 2002); and P2RY1, purinergic receptor through which ADP and ATP modulate insulin secretion (Fernandez-Alvarez et al 2001).…”