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RAF proteins in the RAS-RAF pathway

The RAF proteins are a family of kinases that serve as an intermediary in transmitting extracellular signals from growth factor receptors in the RAS-RAF pathway, a type of MAPK signaling pathway. This pathway controls cell growth, cell proliferation, and cell differentiation.^1,2

The RAS-RAF pathway is a highly conserved pathway necessary for normal cell function. Some biological processes that the pathway controls include cell growth, cell proliferation, and cell differentiation.¹

In normal cells, growth factors bind to and activate receptor kinases, which causes a downstream signaling cascade. This eventually leads to the transcription of genes that encode proteins. These proteins regulate essential cellular functions.

RAS-RAF signaling is initiated by receptor tyrosine kinases upon their activation by growth factors in the extracellular space.³

1. Activation of the protein RAS causes the membrane recruitment and activation of RAF proteins.³
2. In turn, activation of RAF leads to the phosphorylation of MEK, another protein kinase.³
3. Next, MEK phosphorylates ERK, a type of MAPK, which can directly and indirectly activate many transcription factors.³
4. The activation of these transcription factors then leads to the expression of genes that regulate cell proliferation and survival.³

When mutations in genes within this pathway occur, this could lead to constitutively active proteins. This results in increased cell proliferation and resistance to apoptosis (programmed cell death), both of which can drive cancer.^1,3

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