Figure 6.

Activation of tTG during apoptosis of U-937 cells induced by Amph variants 1-4 and by Onc. The cells, incubated for 72 h in the absence (Ctrl) or presence of Amph 1-4 variants at 1 µg/ml concentration, or with 5 µg/ml Onc, were treated with a solution of nonionic detergent Triton X-100 containing the DNA fluorochrome DAPI and the protein fluorochrome sulforhodamine 101. The nonapoptotic cells were lysed under these conditions, releasing isolated nuclei that stain minimally with sulforhodamine 101. In contrast, apoptotic cells (Ap) with activated tTG having crosslinked proteins, withstand the detergent treatment, their cytoplasmic proteins stain strongly with the sulforhodamine 101 while DNA, due to extensive fragmentation and chromatin condensation, stains at lower intensity compared to nonapoptotic cells.25,29