During development, groups of cells communicate with each other using protein messengers that are secreted from one cell and bind to receptors on neighbouring cells. One important family of protein messengers are called Wnts (pronounced wints). When the message is received, the responding cell switches on a number of genes in its nucleus that in turn bring about changes to processes such as growth and cell type. The connections inside the cell that transmit the Wnt signal from the cell surface to the nucleus are very important since they control how the signal is amplified and aimed at the right genes. The proposed research will use a method to the order in which connecting Wnt signalling components function inside the cell. The basic idea is to use a very sensitive cells that have been engineered to send out a burst of light when the Wnt signal is active in the nucleus. We then use a new method called RNAi to remove proteins that might be Wnt connecting components. If the protein IS required, the burst of light will be lost. This question is asked again and again for many genes using robots to speed up the process. We can ask whether and how many genes are required for Wnt signalling Once we know which proteins are involved in the Wnt pathway, we can study how they work and how they control animal development.