FIG. 5.

Phosphorylation inhibits the binding of Myc to DNA. Pak2 and various alleles of Myc were expressed by transfection into 293T cells. Analysis of cellular extracts for the binding of Myc and endogenous Max to E-box oligonucleotide was performed as described in Materials and Methods. (A) Coprecipitation of Myc and Max with biotinylated E-box oligonucleotide. Precipitated Myc and Max were detected by immunoblotting. Aliquots of cell lysates used in the binding assays were subjected to SDS-PAGE and immunoblotting for Myc. (B) Quantification of results. The histogram illustrates the mean and standard deviation of three independent experiments, quantified with ImageQuant (*, P < 0.005; **, P < 0.02). (C) Coprecipitation of endogenous Myc and Max with E-box DNA was detected by immunoblotting as in panel A.