Model for the role of Ras1 activity inhibition for mating progression. During the exploratory phase (top), when cells are not yet in contact, Gap1 recruitment to Ras1-GTP sites promotes the disassembly of the polarity patch. As cell proximity increases, the positive entrainment between partner cells increases. This consists in local pheromone release from one cell leading to local signal activation in its partner, and results in local Ras activity increase, which overcomes the negative regulation by Gap1, and promotes MAPK recruitment to the fusion focus, leading to its stabilization. When Ras1 is constitutively activated, the fusion focus is stabilized early, before cells are in contact, thus resulting in cell lysis.