PTPN1 and pancreatic insulinoma: Several lines of evidence support a role for Ift88 and cilia function in EphA-processing: (A) treatment with EphrinA5-Fc reduces EphA phosphorylation levels and restores insulin secretion to the levels of control islets or insulinoma cells; (B) overexpression of a dominant negative isoform of EphA5 (DN-EphA5) partially rescues glucose-stimulated insulin secretion in Ift88-depleted MIN6m9 cells; (C) overexpression of human Ptpn1, encoding for Ptp1b, one of the main negative regulators of EphA receptors, also restores insulin secretion in Ift88-depleted MIN6m9 cells.