FIG. 9.

The DTVD→A mutant has a reduced ability to promote DNA fragmentation in HEK293 cells. HEK293 cells were transfected with 1 μg of MEKK1.cp4, DEVE_A.cp4, or DTVD_A.cp4 and processed as described in the legend to Fig. 5. (A) Nomarski views (magnification, ×40) of HEK293 cells transfected with wild-type MEKK1 or the indicated mutants and overlaid with fluorescent staining for MEKK1 expression (red staining) and for DNA fragmentation (green staining). (B) Quantitation of the percentage of MEKK1 mutant-transfected cells that showed DNA fragmentation. The numbers in the columns indicate the number of cells transfected with the MEKK1 mutants and counted on at least four coverslips from at least two different experiments.