TAX1BP2 was initially identified as a novel centrosomal protein that interacts directly with the human T-cell leukemia virus type 1 (HTLV-1)-encoded oncoprotein, Tax, and inhibits centrosome overduplication. Subsequently, TAX1BP2 was found to be a tumor suppressor in hepatocellular carcinoma, and accumulation of TAX1BP2 was observed upon chemotherapeutic drug treatment. Here, we provide evidence that TAX1BP2 is a direct phosphorylation substrate of ATM. The protein level of TAX1BP2 is significantly upregulated in response to DNA damaging agents.