Ras palmitoyl transferase (Erf2) is localized to the ER (Bartels et al., 1999) . Thus, there currently appears to be marked differences in the palmitoylation pathways of mammalian and yeast Ras proteins, which might reflect reported differences in the intracellular trafficking itineraries of these proteins (Dong et al., 2003; Wang and Deschenes, 2006) .