Intracellular localisation of PrPC in the human pancreas. Specific co-staining of PrPC and cellular markers for ER (WFS1), Golgi (GM130) and cell membrane (CD99) staining was implemented to assess PrPC intracellular localisation within endocrine cells of the human pancreas. PrPC was found to co-register with WFS1 (a, d, g) and CD99 (c, f, i) but not GM130 (b, e, h; ESM Fig. 2) based on 3D image reconstruction analysis (insets), indicating that PrPC is mainly associated with the ER and plasma membrane of pancreatic endocrine cells. Scale bars, 20 μm. ND, non-diabetic, T1D, type 1 diabetic