Immunocytochemical detection and analysis of recombinant polyserase-3 expression in human cell lines. A, image captures by fluorescence microscopy of 293-EBNA cells transfected with pCEP-pol3 vector and incubated with an anti-FLAG antibody, followed by incubation with a secondary fluorescein-conjugated antibody (FITC). This signal was not detected in cells transfected with an empty vector. The observed cytoplasmic fluorescence indicates that polyserase-3 is not a membrane-anchored protease. DNA in the cell nucleus was visualized with DAPI. B, representation of the recombinant polyserase-3 containing the indicated epitopes, and Western blot analysis of 293-EBNA cells and conditioned medium using an anti-FLAG antibody. Equivalent results were obtained using an anti His-Tag antibody (not shown). C- indicates cells or conditioned medium from cells transfected with the empty vector, and T indicates sample treated with 1 μg/mL tunicamycin. The concentration of the SDS-PAGE gel was 12%, and the molecular mass markers in kDa are indicated on the left.