PRLR and tumor of parathyroid gland: PRLR-total expression was observed in 35/37 parathyroid tumours, at levels that are higher (>1.5, n = 7), lower (<0.5; n = 9) or comparable (>0.5 and <1.5; n = 19) to the mean level for the normal parathyroids (0.77–1.30).