NTAN1 and viral infectious disease: Interestingly, NTAN14KA is significantly more stable than NTAN1WT (Figures 6D, F and H); additionally, unlike NTAN1WT (Figure 6A, lanes 1 vs. 5), blocking the proteasome by MG-132 treatment did not show any effect on the protein level of NTAN14KA in the absence of viral infection (Figure 6C, lanes 1 vs. 4), suggesting that one or all of these lysine residues and/or polyubiquitylation have some contribution to the protein stability of NTAN1.