Numerous studies have revealed that A20 negatively regulates NF-κB signaling pathway by inhibiting the function of several NF-κB upstream signaling transducers.15, 16, 17, 18, 19 and 20 Activation of NF-κB signaling pathway has a crucial role in the development and progression of NPC.9, 10, 11 and 12 Therefore, we investigated whether A20 mediates miR-125b-regulating NPC cell proliferation and apoptosis by activating NF-κB. We observed that miR-125b mimic or A20 KD enhanced, whereas miR-125b inhibitor or A20 overexpression reduced the activity of NF-κB signaling pathway in NPC cells. This evidence concerns the gene TNFAIP3 and nasopharyngeal carcinoma.