In this grant we will determine how cell shape (polarity) regulators affect cell survival in an epithelial tissue. When cell shape regulators are perturbed in a cell within a tissue, through mutation or upon wounding, signalling pathways are altered that trigger death of the aberrant cells. Activation of a surveillance mechanism termed "cell competition" is important to remove the damaged cells. In this grant, we investigate a potential novel regulator of cell competition, the tyrosine phosphatase PTP61F, in response to perturbation of cell shape regulators, using the vinegar fly, Drosophila, and mammalian systems. This study will reveal new biomarkers that can be used to manipulate cell competition to improve fitness or for pest control.