Only in members of the gammaherpesvirus subfamily does the SOX protein have an additional mRNA turnover function. Although the precise mechanism by which these proteins cause mRNA degradation remains unclear, biochemical evidence suggests that at least EBV BGLF5 and KSHV SOX possess some intrinsic ribonuclease (RNase) activity in vitro [21, 22] . In addition to mRNA turnover, SOX promotes the nuclear relocalization of cytoplasmic poly(A) binding protein (PABPC), which leads to aberrant polyadenylation and nuclear retention of mRNAs [23, 24] . The failure to repopulate the cytoplasm with newly transcribed mRNAs is thought to increase the overall magnitude of the host gene expression blockade [23] .