INVOLVEMENT OF C-SRC IN BETA-CASEIN EXPRESSION BY MAMMARY EPITHELIAL-CELLS

HC11 mouse mammary epithelial cells were stably transfected with c-src or a dominant negative mutant of c-src driven by a MMLV promoter. Pro lactin increased c-src activity in control and c-src transfected cells , while dominant negative c-src reduced the prolactin-induced increase in c-src activity. Dominant negative c-src also reduced the ability o f insulin, hydrocortisone, and prolactin to induce beta-casein accumul ation to levels one-half to one-third that of control cells. This effe ct was uncorrelated with any change in cell proliferation or laminin a ccumulation and was observed both in cultures grown to confluency in t he presence of EGF and in cultures grown on laminin. (C) 1997 Academic Press.