Alternatively, elevated serum OPG at baseline may mirror elevated OPG expression in primary CRC tumors with high propensity to metastasize, which has been explained by autocrine OPG-dependent prevention of tumor cell apoptosis via inhibitory binding of the TNF-related apoptosis-inducing ligand [31, 32]. The gene discussed is TNFRSF11B; the disease is colorectal carcinoma.