Myc, Mad, and Max protein synthesis in U-937-myc-6 and U-937-GTB cells. (A) U-937-myc-6 and U-937-GTB cells were treated with TPA for 3 days before ³⁵S-methionine labeling. High stringency lysates were immunoprecipitated with pan-Myc (IG-13), Mad1 (C-19), and Max (C17) antibodies and analyzed by SDS-PAGE. (B) Time course of Myc, Mad1, and Max proteins synthesis during stimulation of U-937-myc-6 cells. TPA, IFN-γ, or TPA + IFN-γ were added for the time indicated and the proteins were analyzed as in (A).