B2M and neoplasm: The β2M/hemochromatosis protein (HFE) complex could induce epithelial to mesenchymal transition (EMT), which promotes bone and soft tissue metastases of human prostate, breast, lung, and renal cancer cells in vivo by activating the iron-responsive hypoxia-inducible factor-1α (HIF-1α) signaling pathway [14], and β2M could promote tumor growth through the activation of the vascular endothelial growth factor receptor-2 (VEGFR-2)/Akt/mammalian target of rapamycin (mTOR) signaling pathway in ovarian cancer [15].