TRIM21 and systemic lupus erythematosus: Since Ro52β contains both the N-terminal and C-terminal domains (Figure 3B), it is likely that the ~45 kDa band detected in PBMCs by antibodies to the N-terminal and C-terminal regions of Ro52 (Figure 1, G and H, respectively) corresponds to Ro52β, which is consistent with the upregulation of its transcript in SLE monocytes (Figure 2C).