For instance, in OPC protein–protein interaction (PPI) network, proteins involved in Golgi vesicle transport (such as Vamp3, Golga7, Vti1b and Snx1), Cell redox homeostasis (such as Tnx2 and Gsr), nervous system disease (such as Got1, Gm2a, Apoe and Cst3) and other functions were identified (Fig. 4b). Here, APOE is linked to nervous system disorder.