PAQR7 and breast carcinoma: Also, studies using nPR-deficient mammalian breast cancer cells, MDA-MB-231, transfected with zebrafish mPRα and mPRβ and exposed to 17α,20β-DHP show that both receptors mediate their effects through activation of the MAPK pathway, which subsequently decreases cAMP levels (Hanna et al. 2006).