Figure 3.
MKP-1 cytoprotection against UV-induced apoptosis correlates with inhibition of SAPK activity. (A) U937 cells expressing hMTIIa-MKP-1 were pretreated with the indicated concentrations of CdSO4 for 4 h before exposure to UV radiation (200 J/m2) and after 30 min whole-cell lysates were prepared. SAPK activity was determined as described (28). (B) Cells were treated as above and caspase-3 activity (○) was determined 8 h postirradiation and is plotted together with SAPK activity (▪) as determined in A above. (C) Cells were treated as described above and DNA fragmentation was analyzed 8 h postirradiation as described in Fig. 2. DNA fragmentation was also quantified by FACS analysis and is reported under each lane (% frag).