Meta-Biol

• Pathways

In many cancer types, RAF1 (also known as CRAF) appears to be a critical initial effector of the ERK pathway downstream of activated RAS and also mediates pathway activation in the presence of WT BRAF plus BRAF inhibitors (Rushworth et al, 2006; Dumaz et al, 2006; Garnett et al, 2005; Karreth et al, 2011; Poulikakos et al, 2010; Heidorn et al, 2010; Roring et al, 2012; reviewed in Samatar et al, 2014; Lito et al, 2013). This activation depends largely on heterodimerization with BRAF, although homodimers also contribute (Weber et al, 2001; Rushworth et al, 2006). Activation of RAF downstream of mutant RAS appears to require full phosphorylation of the N-region and the activation loop, unlike the case in BRAF mutant cells, where RAF N-loop phosphorylation is dispensable (Garnett et al, 2005).