A MAPK cascade containing at least the Fus3 MAP kinase. It starts with the activation of Ste20, a MAP4K, which activates Ste11, a MAP3K, which in turn activate Ste7, a MAP2K, which activates Fus3. The kinases in each tier phosphorylate and activate the kinases in the downstream tier. This MAPK cascade is triggered by a pheromone activating its G protein-coupled receptor, and results in cellular responses that lead to conjugation with cellular fusion.
MAPKKK cascade involved in mating response