FIGURE 4.

MDM2 binds directly to ATF3. A, H1299 cells were transfected as indicated and lysed for IP assays using the ATF3 antibody (α-ATF3) or IgG. Precipitated proteins were subjected to immunoblotting (IB) to detect MDM2 and ATF3. B, LNCaP cell lysates were incubated with the ATF3 antibody or IgG at 4 °C overnight. Immunoprecipitated proteins were then subjected to immunoblotting. C, 100 ng of purified ATF3 protein was incubated with 200 ng of purified GST-MDM2 protein or BSA at 4 °C overnight. Protein complexes were pulled down by glutathione-agarose and subjected to immunoblotting.