BRAF and cancer: Resistance emerges through upregulation of expression of mutated BRAF, alternative splicing of BRAF transcript, secondary BRAF mutations, mutations in genes encoding MEK1/2 and RAS, reactivation of COT (cancer osaka thyroid oncogene) activity, dimerization of CRAF (RAF-1 proto-oncogene, serine/threonine kinase), which all can lead to the hyperactivation or recovery of the MAPK pathway activity.