Professor Holmgren’s research studies how cells in a developing organism signal to one another to pattern tissues. Drosophila is primarily used as a model system and the role of the Hedgehog signal transduction cascade in the patterning of the wing is studied. Of particular interest is how the range of Hedgehog signaling is regulated, how different modes of regulation lead to robust, reproducible outcomes, and how Hedgehog signaling is integrated with other cellular processes. The approach is to identify new components in the pathway using various genetic interaction screens and to then characterize the function of the encoded proteins.