As with previous proteomics investigations of subcellular components, we anticipate that further refinement over time will be possible and will yield a more detailed picture of the effects of adenovirus on this important structure both at the 18-h postinfection time point analyzed here and other time points. Also of note is the lack of viral proteins identified by either method. In part, this is a consequence of the time point chosen as the expression of late adenovirus proteins that are known nucleolar antigens would have only just begun. Other explanations are inherent in the methodology; i.e. the viral proteins may dissociate from nucleoli under the conditions present in the nucleolar isolation protocol.