STING1 and viral infectious disease: Since an antibody against K11-linkage of polyubiquitin chains was not available to us, THP-1 cells stably transfected with Flag-Ub-K11O (THP-1-Flag-Ub-K11O) together with a control or RNF26-RNAi plasmids (Figure 4C and D) were established to examine viral infection-induced K11-linked polyubiquitination of MITA and the role of RNF26 in this ubiquitination.