To gain insight into the putative biological functions of the identified proteins, differentially phosphorylated proteins were functionally annotated and classified by using the functional annotation tool of Database for Annotation, Visualization and Integrated Discovery (DAVID) [47, 48] bioinformatics resources (http://david.abcc.ncifcrf.gov) on the National Institute of Allergy and Infectious Disease (NIAID). This software performed a statistical analysis based on gene ontologies to identify groups that were significantly overrepresented (enriched) in this filtered data set. Upon DAVID gene functional classification, there were two groups of annotated proteins identified that showed statistically significant enrichment scores; they included phosphoproteins and those that were posttranslationally modified by acetylation (Fig. 3B ). In addition, these proteins with significant enrichment scores were separated to nucleus and cytoplasm in location. And the proteins that function in the nucleus were remarkably represented by those that control mRNA processing, chromosome organization, chromatin assembly/disassembly, DNA packaging, etc, (Fig. 3B) .