FIBROBLAST GROWTH-FACTOR RECEPTOR SIGNALING HAS A ROLE IN LOBULOALVEOLAR DEVELOPMENT OF THE MAMMARY-GLAND

We have used the mouse mammary tumor virus promoter to express two dom inant negative (DN) fibroblast growth factor receptor (FGFR) isoforms in the mammary epithelium of transgenic mice. While expression of DN-F GFR1(IIIc) showed no discernible phenotype, a similar kinase negative form of FGFR2(IIIb) caused a marked impairment of lobuloalveolar devel opment, The growth retardation was apparent by mid-pregnancy and persi sted in the post-partum glands. Despite the substantial underdevelopme nt of the mammary gland there was a measurable lactational response, b ut it was insufficient to properly sustain the new-born pups, These fi ndings demonstrate that fibroblast growth factor signalling is necessa ry for pregnancy dependent lobuloalveolar development of the mammary g land.