Figure 4.

Effect of staurosporine treatment on U3A cells complemented with wild-type and N-terminal mutants of Stat1. (A) EMSA analysis with an M67 probe. Whole-cell extracts were prepared from U3A cells complemented with wild-type human Stat1 (p91) treated with IFN-γ for 30 min followed by staurosporine (500 nM) for the indicated times. (B) Same as A except U3A cells complemented with Stat1 containing a mutation in arginine 31 to alanine (U3R). (C) Plot of the PhosphorImager analysis of Stat1 DNA binding complexes in U3A cells complemented with different Stat1 constructs (p91, p84, U3R, and Δ154) at various times after IFN-γ and staurosporine treatment. The results shown are the average of two experiments with error bars representing the SEM.