In addition to immune system function, a number of the vitamin PPI network hubs play a role in cell cycle control and cancer progression (NFKB1, KPCA, SMAD3, RXR, VDR, SMCA4, TNFα, TFE2), reflecting previous findings that cancer-related proteins are more highly connected than non-cancer-related proteins [52]. This evidence concerns the gene TNF and cancer.