PRL and hyperprolactinemia: In Wistar-Furth rats inoculated with these same transfectants, treatment with lapatinib led to a 40% suppression of adenoma growth and 50% decrease in PRL levels (82), and Fischer rats implanted with estrogen pellets to recapitulate an endogenous prolactinoma model developed pituitary adenomas with hyperprolactinemia that were suppressed by 35% with lapatinib treatment (82).