Hypercalcemia is also observed in more than 80% of adult T-cell leukemia/lymphoma (ATLL) patients at diagnosis, and a significant role in its presentation may be played by a high serum MIP-1α level, spontaneously produced by ATLL cells, which induces the expression of RANKL on these cells and the differentiation of monocytes into osteoclasts [10]. The gene discussed is TNFSF11; the disease is adult T-cell leukemia/lymphoma.