Send to:

Choose Destination
See comment in PubMed Commons below
Proc Natl Acad Sci U S A. 1981 Sep;78(9):5682-4.

Insulin is essential for accumulation of casein mRNA in mouse mammary epithelial cells.


In the presence of cortisol and prolactin, insulin at concentrations as low as 1 ng/ml significantly stimulates casein synthesis in mammary explants from midpregnant mice; maximal synthesis occurs at 10 ng/ml. However, in the absence of insulin, no detectable immunoprecipitable casein is produced. Insulin also supports enhanced accumulation of casein mRNA in the presence of cortisol and prolactin; neither epidermal growth factor nor somatomedin C has this effect. These inductive actions of insulin are not secondary to a general maintenance effect on the mammary epithelial cell; insulin, epidermal growth factor, and somatomedin C can support the accumulation of RNA in rough endoplasmic reticulum equally well. In addition, these effects do not reflect a specific insulin requirement for prolactin sensitivity; epidermal growth factor can support prolactin-induced total RNA synthesis as well as insulin can. The results demonstrate that, although insulin, epidermal growth factor, and somatomedin C can all function as cell maintenance agents, only insulin, together with cortisol and prolactin, can induce casein mRNA accumulation.

[PubMed - indexed for MEDLINE]
Free PMC Article
PubMed Commons home

PubMed Commons

How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for PubMed Central
    Loading ...
    Write to the Help Desk