The MAPK signaling proteins are involved in many eukaryotic cellular processes and signaling networks. The upstream activation pathways for ERK1 and ERK2 are highly similar, and also many of their known downstream targets are common; however these genes exhibit different knockdown phenotypes and there are diverse roles for these kinases during embryogenesis. For ERK1 specific genes are involved in dorsal-ventral patterning and subsequent embryonic cell migration. For ERK2, several genes are involved in cell-migration, mesendoderm differentiation and patterning.