Ubiquitination and deubiquitination are decisive in the regulation of RLR pathways activation [150]. Upon binding to viral dsRNA, RIG-I and MDA5 undergo conformational changes and release the N-terminal tandem CARD domains [151,152,153]. The CARD domains of RIG-I are modified by lysine 63 (K63) polyubiquitin chains through the ubiquitin ligases TRIM25, RNF135, and RIPLET. This modification is crucial for RIG-I to recruit MAVS [154,155]. In addition to the ubiquitination of RLRs, the polyubiquitylation of TRAF3 and TRAF6 also play an important role in the regulation of innate immune signaling by activation of TBK1 and IKKs, respectively. The K63 polyubiquitin chains can be removed by DUBs such as the tumor suppressor protein CYLD, DUBA and A20, providing a mechanism to downregulate immune responses [156]. Ubiquitination and deubiquitination are in a dynamic equilibrium to maintain immune homeostasis.