TRIM21 and polymyositis: RNP: ribonucleoprotein, Sm: Smith, SSA: Sjogren’s syndrome type A, Ro52: recombinant Ro52, SSB: Sjogren’s syndrome type B, Jo1: histidyl-tRNA, Scl-70: scleroderma/topoisomerase, CB: centromere B, dsDNA: double-stranded DNA, histones: his, PCNA: proliferating cell nuclear antigen, Nuc: nucleosomes, Rib: ribosomal protein, M2: mitochondrial antigen, PM/Scl: polymyositis/scleroderma