Fig. 5. Inhibition of the prolactin signalling pathway by colchicine. Primary mammary epithelial cells were cultured on basement membrane and exposed to colchicine for the indicated times. Prolactin was added to the cultures 15 minutes before harvesting the cells as in Fig. 3. (A) Nuclear extracts were analysed by electrophoretic mobility shift assay for Stat5-DNA interactions. (B-E) Detergent lysates were immunoprecipitated for Stat5 (B,C), Jak2 (D) or PrlR (E) and immunoblotted with antibodies for phosphotyrosine (4G10) or the appropriate precipitating antibody.