MAPK1 and melanoma: In melanoma cells, the mechanism involves a switch in signaling from the standard v-raf murine sarcoma viral oncogene homolog B1 (BRAF) pathway to the extracellular signal-regulated kinase 2 (ERK2) and JUNB proto-oncogene, AP-1 transcription factor subunit pathways, because when these two genes were genomically knocked out, the melanoma cells died.