Interaction between the substratum and mesenchyme and regulation by growth factor in mammary glands and reproductive organs.

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1) Involvement of MAP kinase in signal transduction : One of insulin, IGF-I or EGF is essential for mammary growth. MAP kinase exists in mammary epithelial cells. 2) Regulation of the expression of prolactin receptor : Prolactin receptor is induced by glucocorticoids in the mammary gland. This induction was demonstrated by the competitive PCR method at the level of transcription. 3) Responsiveness of HC11 to prolactin : HC11, a cell line derived from normal mammary epithelial cells, responses very poorly to prolactin. To improve the responsiveness, cDNA for long-form prolactin receptor was introduced to HC11 cells. No highly responsive clone was obtained yet. 4) Effect of hepatocyte growth factor on mammary tumour growth : A growth factor contained by fibroblast conditioned by the Baculo virus vector system. Antibody against the protein inhibits tumour cell growth. 5) Estasblishment of cell lines from tissues of p53-deficient mice : Many cell lines were established from nerves, seminal vesicles and mammary glands. 6) Effect of EGF on glucose incorporation in early embryos : Early embryos cannnot utilize glucose becouse hexokinase is not expressed until the blastocyst stage. GLUT 1, a protein which promotes glucose incorporation, expresses at the blastocyst stage for the first time. EGF stimulates this expression. 7) Regulation of luteal function by IGF-I and its binding proteins : To investigate the regulation, expressions of IGF-I and IGFBP3 in corpora lutea were investigated by dot blotting and northern blotting analysis. IGF-I increased until parturition.