PCNA and connective tissue disorder: Connective tissue disease screening including U1 small nuclear ribonucleoprotein particle (U1-snRNP), Sjögren's syndrome-related antigen A autoantibodies (SS-A/Ro), Sjögren's syndrome type B (SS-B/La), centromere protein B (CENP-B), topoisomerase 1 (Scl-70), anti-histidyl transfer RNA [t-RNA] synthetase) (Jo-1), Sm, anti-double-stranded deoxyribonucleic acid (dsDNA), fibrillarin, RNA Pol-III, ribosomal P proteins (Rib-P), overlap syndrome of polymyositis and scleroderma (PM-Scl), proliferating cell nuclear antigen (PCNA), and Mi2 was not informative.