Substratum modulation of epidermal growth factor receptor expression by normal mouse mammary cells.

Normal mouse mammary cells synthesize the basement membrane scaffold on which the cells rest in vivo. This extracellular matrix material serves important functions in the growth and differentiation of the mammary epithelium. Components of the basement membrane negatively regulate basement membrane collagen biosynthesis in response to epidermal growth factor stimulation. This effect is shown to correlate with changes in growth factor receptor regeneration following ligand-induced receptor down-regulation. The results suggest that while control of basement membrane synthesis may be manifest in part by the availability of growth factors, the environment in which the mammary cell finds itself is also very important.