Presumably, the possible relation between Treg cells and hypercalcemia could be explained by the cytokine production including tumor necrosis factor (TNF-α), vascular endothelial growth factor (VEGF), colony stimulating factor (CSF), IL-10 and TGF-β at the tumor site which prominently recruit osteoclasts and might also aid in expansion of Treg cells. This evidence concerns the gene CSF2 and hypercalcemia disease.