Decreased expression of TRIM21 has been found in hepatocellular carcinoma, diffuse large B-cell lymphoma and breast cancer, and was associated with a poor prognosis and enhanced proliferation capacity of cancer cells in vitro and tumor growth in vivo (Brauner et al., 2015; Ding et al., 2015; Zhou et al., 2018). Here, TRIM21 is linked to breast carcinoma.