In 2004, the first papers detailing the roles of microRNA in hematopoiesis were published by the labs of David Bartel and Harvey Lodish. Since then, there have been a plethoraof discoveries of how microRNAs influence hematopoiesis, and this has led to a better understanding not only of hematopoeisis but of how microRNAs may function in development in general. Some general themes which are emerging include the idea that some microRNAs act primarily through a single target at critical points of development, or that microRNAs may serve as organizing loci for complex developmental pathways of, finally, that microRNAs connect disparate cellular pathways whose interconnections were previously unrecognized. Our current research has come to focus on microRNAs that are dysregulated in myeloid malignancies in humans. We and others have found that miR-146a is dysregulated in myelodysplastic syndrome. The future of these studies is currently to understand how NF-kappa B dysregulation may result in the range of myeloid and hematopoeitic phenotypes that we are observing. To do so, we are collaborating with the laboratory of Alex Hoffmann.