Human epithelial cell extract. Contains the following antigenic components from human whole cell extract as tested by western blot: SS-A (Ro) with 60kD and 52kD bands, SS-B (La) with 50kD band (note that the SS-A 52kD and the SS-B 50kD bands overlap due to their size), Scl-70 (topoisomerase I) with 105kD band, RNP with 68kD and 33kD bands, Smith with 26kD and 25kD bands, Jo-1 with 53kD band, and Ribosomal P with 38kD band. Bands are present using Western blot qualified antisera. Other antigens may be present.