The Miller Lab is interested in how epithelial tight junctions remodel to maintain barrier function when cells change shape. In previous work, we reported that transient, localized accumulations of active RhoA at cell-cell junctions, which we termed “Rho flares”, are associated with junction remodeling. We found that Rho flares repair local leaks in barrier function through actomyosin-dependent junction contraction that reinforces tight junctions (Stephenson et al., 2019, Developmental Cell; Varadarajan et al., 2022, Journal of Cell Biology). In this new paper, which was featured on the cover of Molecular Biology of the Cell, we investigated which RhoGEF activates RhoA at sites of local tight junction remodeling. We found that p115RhoGEF activates Rho flares and plays a critical role in maintaining junctional RhoA to support apical actomyosin and cell-cell junctions in order to preserve epithelial barrier function.