In our study, published Mar 9 in Science, we found the novel role of Gli2, the major Hedgehog pathway transcription effectors, on the regulation of a niche signaling program for mammary epithelial stem cells. The mammary gland niche support its associated stem cells while also responding to systemic hormonal regulation that triggers pubertal changes. We found that Gli2 acts within mouse mammary stromal cells to direct a hormone-responsive niche signaling program by activating expression of factors that regulate epithelial stem cells as well as receptors for the mammatrophic hormones estrogen and growth hormone. Whereas prior studies implicate stem cell defects in human disease, this work shows that niche dysfunction may also cause disease, with possible relevance for human disorders and in particular the breast growth pathogenesis associated with combined pituitary hormone deficiency (CPHD).