Collective and planktonic cell migration are important for epithelial cell homeostasis, recovery from injury, infection or inflammation. There has been considerable focus in understanding how structural and mechanical forces are balanced in this process and how certain signaling pathways such as chemokines are involved. It is known that signaling by stable reactive oxygen species (ROS), such as hydrogen peroxide, is involved in cell migration but exactly how and what aspects of migration are controlled by ROS are less understood.  Our studies suggest that ROS near to the migrating edge of the cell is involved in controlling the direction of cell migration, although the mechanisms involved remain unclear. We are investigating these questions using a combination of live high-resolution ratio imaging using ROS biosensors, and chemo-genetic approaches.