CASR and tumor of parathyroid gland: CaSR can function as an inhibitor of cell proliferation in parathyroid tumors, which was demonstrated in rodents treated with cinacalcet.21 Interestingly, in addition to activating CaSR, calcimimetics also seem to increase CaSR expression.22 It is thus possible that in the present case, cinacalcet not only decreased serum calcium concentrations but also had an effect on CaSR expression and tumor proliferation.