TMEM219 and pancreatic insulinoma: A low expression of both TMEM219 mRNA and protein (Figures 3D, E) and a high mRNA expression of MKI67 (Figure 3F), were evident in the insulinoma samples, with circulating levels of the TMEM219 ligand IGFBP3 also being reduced (Figure 3G), thus suggesting a dysregulation of the TMEM219 signaling.