Several protein phosphatase encoding genes were also differentially expressed, such as PPM1M, PPP2R4, PPP3CA, etc. However, the magnitudes of differential expression in these genes were small and there were only two transcripts showed |log2 fold-change| >1.5: IFI27 was consistently upregulated in the influenza virus group on days 0–6 but not upregulated in the rhinovirus or other infection groups (Fig 2F); in addition, PI3 was consistently downregulated in the influenza-infected individuals but not in the other groups (Fig 2G). Here, PI3 is linked to infection.