The Ras pathway is a critical si
gnal transduction cascade involved in
regulating cellular proliferation, differentiation, su
rvival, 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 M
EK and ERK (Marshall, 1996). Previous studies have
shown that phosphorylation is required for Raf-1 ac
tivation (Dhillon and Kolch, 2002; Chong et al., 2003).
Recent work has demonstrated that phosphorylation al
so regulates the downregulation of Raf (Dougherty
et al., 2005) with two sites participating: Ser
301
and Ser
642
.
