PTEN and pancreatic insulinoma: Since we are interested in inducing benign, rather than malignant growth of beta cells, it was reassuring to observe parallels between cell cycle genes and modules in insulinomas and proliferating juvenile beta cells (Fig. 5a, b), and also to observe that mutations in DNA repair genes such as ATRX, DAXX, TP53, BRCA2, CHEK2, and the PI3 kinase/PTEN/mTor/TSC pathway, characteristic of malignant non-functioning PNETs52, 53, were not observed in the insulinomas.