Fig. 9. Atypical apoptotic cells are cleaved caspase-3, p85 of PARP-1 and TUNEL negative. HeLa cells grown on glass coverslips were treated with Fas antibody and PD 98059 in the presence of 30 µM z-DEVD-FMK for 24 hours and double-stained with NuMA (A) and cleaved caspase-3 (B) or NuMA (F) and p85 fragment of PARP-1 (G) antibodies or processed for TUNEL-assay (K). FITC-conjugated goat-anti-mouse (A and F) and TRITC-conjugated goat-anti-rabbit (B and G) secondary antibodies were used. Samples were counterstained for DNA with Hoechst (D, I and L). Atypical apoptotic cells (arrowheads) are NuMA and TUNEL negative and do not stain with cleaved caspase-3 or p85 fragment of PARP-1 antibodies. Typical apoptotic cells (arrows) stain with all studied antibodies and are TUNEL positive. Note the single cell (star, A-E) which stains weakly for NuMA and cleaved caspase-3 and shows abnormal chromatin structure. The phase contrast view shows that both typical and atypical apoptotic cells have shrunken and partially detached. Bar 10 µm.