In one of the first studies addressing the role of sex hormones' impact on stem cells in the gut, scientists outline new insights showing how a steroidal sex hormone, that is structurally and functionally similar to human steroid hormones, drastically alters the way intestinal stem cells behave, ultimately affecting the overarching structure and function of this critical organ. The authors found that ecdysone, a steroid hormone produced by fruit flies, stimulates intestinal stem cell growth and causes the gut of the female fruit fly to grow in size, and induces other critical changes. The study also provides a mechanism to account for sex-specific roles for intestinal stem cells in normal gut function. Moreover, the research presents evidence that gut hormones may accelerate tumor development. The findings, reported jointly by Huntsman Cancer Institute (HCI) at the University of Utah (U of U) and the German Cancer Research Center (DKFZ), are published today in the journal Nature.