Cleavage of 70 kDa U1-snRNP in COS-7 cells transfected with pEGFP-NS1. (A) Expression of various autoantigens including 70 kDa U1-snRNP, Sm, Ku, CENPA/B, Scl-70, SSA/Ro, SSB/La and Jo-1 (lane 1-2, 5-7, 9-11) were detected in COS-7 cells transfected with pEGFP, pEGFP-NS1 and pEGFP-NS1K334E by various antibodies. Actin is used as control (lane 3) and arrow indicates a cleaved 40 kDa U1-snRNP protein. (B) Ratio of 40 kDa U1-snRNP to actin. (C) The presence of 70 kDa and 40 kDa U1-snRNP were detected in COS-7 cells transfected with (lanes 1 to 4) pEGFP, pEGFP-NS1, pEGFP-NS1K334E and pEGFP-NS1 with caspase-9 inhibitor by antibodies against U1-snRNP. (Lane 5) Actin is used as control. Three independent tests were performed. * and # indicate significant difference as compared to E or N, respectively. E, N and K indicate EGFP, EGFP-NS1 and EGFP-NS1K334E, respectively.