MAPK cascade ERK1 and ERK2 cascade An intracellular protein kinase cascade containing at least ERK1 or ERK2 (MAPKs), a MEK (a MAPKK) and a MAP3K. The cascade may involve 4 different kinases, as it can also contain an additional tier: the upstream MAP4K. The kinases in each tier phosphorylate and activate the kinase in the downstream tier to transmit a signal within a cell. ERK cascade ERK1 and ERK2 signaling pathway ERK1 and ERK2 signalling pathway ERK1 cascade ERK1/2 cascade ERK2 cascade GO:0070371 MAPK1 cascade MAPK3 cascade Note that this MAPKKK cascade is commonly referred to as the ERK pathway in the literature, but involves only ERK1 or ERK2 and should not be confused with cascades that involve other ERK kinases. biological_process extracellular signal-regulated kinase 1/2 (ERK1/2) cascade extracellular signal-regulated kinase 1/2 cascade