Deciphering Signaling Pathways In Vivo: The Ras/Raf/Mek/Erk Cascade

The Ras/Raf/MEK/ERK cascade is a highly conserved signal transduction module, whose activation results in a number of different physiological outcomes. Depending on the cell type or the stimulus used, the pathway has been implicated in proliferation, differentiation, apoptosis, and migration. Because of this wide range of activities, these kinases are considered attractive (anticancer) therapeutic targets. However, their essential functions in the context of the whole organism are still incompletely known. Here, we describe immunohistochemical and immunofluorescence methods that can be used to define the essential function(s) and the relevant downstream targets of Raf-1, B-Raf, and Mek-1 in in vivo models of organ development, remodeling, and neoplasia.