Prolactin actions

  1. Karen A Gregerson1,2
  1. 1Program in Systems Biology and Physiology, Department of Molecular and Cellular Physiology
    2James L. Winkle College of Pharmacy, University of Cincinnati, Cincinnati, Ohio 45067-0476, USA
  1. Correspondence should be addressed to N D Horseman; Email: nelson.horseman{at}
  1. Figure 1

    Control of mammary gland lobuloalveolar growth. Hormones from the pituitary gland, placenta, and ovaries converge on mammary epithelial cells that express receptors for estrogen, progesterone (esp. PR-B), and PRL. Activation of receptor-positive cells induces two mediators, IGF2, which acts as a diffusible autocrine–paracrine mitogen, and RANKL, which acts as a juxtacrine mitogen for neighboring cells. The Zn-finger transcription factor GATA3 is permissive for lobuloalveolar growth by inducing IKKα.

  2. Figure 2

    Interactions between hormone-sensing and secretory cells in the alveolar epithelium. Low levels of PRL (thinner arrow) are able to activate hormone-sensing cells and induce RANKL. Higher levels of PRL (thicker arrow) are required to stimulate differentiation of secretory cells. Growth and differentiation of the secretory epithelium are mediated by indirect and direct actions respectively.

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