We also examined the localization of a number of proteins apparently enriched in the nucleolar fraction during infection (Fig. 4) . PP2C is typical of proteins for which we were unable to detect any consistent change in distribution in adenovirusinfected cells (Fig. 4A) . In a similar manner, we were unable to FIG. 2. Typical 2D gel analysis of uninfected cell nucleoli compared with adenovirus-infected cell nucleoli. Isolated nucleoli were subjected to separation in two dimensions prior to staining and visualization as described under "Experimental Procedures." Boxed proteins were consistently seen to vary in intensity in multiple experiments. Those spots were picked for sequencing. Note that spots 4 and 7 were apparently enriched in the nucleolar preparations after viral infection. detect significant consistent changes in the subcellular location of C-NAP1 and nucleoporin 210 (data not shown). However, for PIK3-p87 (Fig. 4B ) and ribosomal protein S15a (Fig.  4C) , we did see some enrichment in the nuclear compartment that could account for the apparent increase in detection in the nucleolar fractions analyzed.