PCNA and scleroderma: anti-U1 RNP: anti-U1 ribonucleoprotein; anti-Ro/SSA: anti-Sjogren’s syndrome-related antigen A autoantibody; anti-La/SSB: anti-Sjogren’s syndrome-related antigen B; anti-Scl-70: anti-scleroderma 70; anti-Jo-1: anti-histidyl TRNA synthetase antibody; anti PM-Scl: anti-polymyositis-scleroderma antibody; anti-PCNA: autoantibody to proliferating-cell nuclear antigen; anti-ds DNA: antibody to double-stranded DNA.