Isg15 and Ifit1/Isg56 (interferon-induced protein with tetratricopeptide repeats 1) mRNA expression were detected 12 h post infection with levels of Isg15 and Ifit1/Isg56 mRNA 5-fold greater in ΔWD MEFs compared to WT controls (Figure 2F). The gene discussed is ISG15; the disease is infection.