Fig. 4. Immunocytochemical analysis of E6-expressing AG05229 cells. (A-D) Cycling E6-infected cells. (E-H) E6-infected cells at M^int. The assays are: PC, phase contrast; p21, immunocytochemical detection of p21^Waf1; SAßgal, histochemical assessment of SAß-gal activity; TUNEL, assay for apoptosis. Arrows indicate multinucleate cells (F) and apoptotic cells (H). All cells except PC are counterstained with haematoxylin. Cell-based assays were done in triplicate. White bar, 100 µm (A,E); black bar, 100 µm (B-D,F-H).