Miyoshi et al. compared the role of the prolactin receptor (PrlR) and its downstream mediator, the signal transducer and activator of transcription 5 (Stat5), in mammary epithelial cells in vivo by studying PrlR-/- and Stat5ab-/- mouse mammary epithelial transplants during pregnancy. At first glance, the two mutant epithelia appear to have similar defects in the differentiation of the alveolar epithelium. However, a closer examination by Miyoshi et al. revealed defects in the epithelial architecture of the smallest ducts of Stat5ab-/- transplants not apparent in the PrlR-/- transplants, suggesting that Stat5 is more than a simple mediator of PrlR action.
Cathrin Brisken, Giovanna Ambrosini, Marian Caikovski, Philipp Bucher, Renuga Devi Rajaram, Patrik Aouad, Dalya Ataca, Marie Shamseddin, Céline Berthe Constantin, Csaba Ferenc László