NPC1 and neoplasm: The average xenograft tumor weight and volume of tumors derived from both cell lines overexpressing VPS33B were decreased compared with the respective negative control (Fig. 1i; Supplementary Figure 1K), while immunohistochemistry (IHC) of proliferating cell nuclear antigen and hematoxylin and eosin staining further confirmed that VPS33B exerted a suppressive effect on proliferation of NPC (Fig. 1j; Supplementary Figure 1L).