The use of modern proteomics approaches to investigate viral infections is still relatively new, but recently several notable studies have been reported that illustrate the power and utility of these techniques (22) (23) (24) (25) (26) . Most of these have used 2D gel electrophoresis-based approaches with some success. For example, 2D electrophoresis was used to examine the total proteome of West Nile virus-infected cells, identifying about 100 different proteins, many of which were clearly upor down-regulated (27) . Much less common is the use of the more powerful quantitative MS coupled with stable isotope labeling by amino acids in cell culture (SILAC) technique to compare uninfected and infected cells. However, one study has investigated the composition of lipid rafts in hepatitis C virus-infected cells, identifying almost 1000 proteins (28) . Furthermore, quantitative MS/SILAC has been extensively used for proteomics analysis of the mammalian nucleolus under a range of conditions (29 -32) . Indeed, a key study examined the changes in composition of the nucleolus after inhibition of rRNA synthesis with actinomycin D (ActD), quantitating the effects on almost 500 proteins in the nucleolus (29) .