In cultured uterine smooth muscle cells from myometrium and leiomyomas, treatment with exogenous PRL has been shown to significantly suppress by 25% to 30% leiomyoma cell proliferation after 5 and 8 days, whereas treatment with a PRL-neutralizing antibody blocked the action of endogenous PRL secreted by the cultured cells and inhibited both myometrial and leiomyoma cell proliferation by about 30% (41). Here, PRL is linked to leiomyoma.