<qa>  What is the dominant role in the MAPK pathway influencing cell growth?Activating mutations in the BRAF gene are present in about 50 of human melanomas. BRAF inhibitors BRAFi inhibit the serine-threonine protein kinase BRAF, which plays a dominant role in the MAPK pathway influencing cell growth. MEK inhibitors MEKi inhibit MEK1 and MEK2, two regulatory proteins downstream of BRAF. 