The Ras pathway is a critical signal transduction cascade involved in
regulating cellular proliferation, differentiation, survival, and oncogenic transformation.
Members of the Raf serine/threonine kinase family are key intermediates in this cascade,
functioning to relay signals from activated Ras to the downstream protein kinases MEK and
ERK (Marshall, 1996). Previous studies have s
hown that phosphorylation is required for Raf-1
activation (Dhillon and Kolch, 2002; Chong et al., 2003). Recent work has demonstrated that
phosphorylation also regulates the downregulation of Raf (Dougherty et al., 2005) with two sites
participating: Ser
301
and Ser
642
