 ERKs are known to activate many transcription factors, such as ELK1, and some downstream protein kinases.Disruption of the ERK pathway is common in cancers, especially Ras, c-Raf and receptors such as HER2.Mitogen-activated protein kinase 1 (MAPK1) is also known as "extracellular signal-regulated kinase 2" (ERK2).