Fig. 1.
Induction of phosphorylation and protein expression of p53 and MDM2 by PS-341.
(A) PS-341 induces p53 phosphorylation (Ser15) and increased protein expression of p53 and MDM2 in MM.1S cells in a time-dependent fashion. Anti–α-tubulin antibody is used to confirm equal loading of proteins. (B) PS-341 induces p53 phosphorylation (Ser15) and increased protein expression of p53 and MDM2 in MM.1S cells in a dose-dependent fashion. Anti–α-tubulin antibody is used to confirm equal loading of proteins. (C) PS-341 induces p53 phosphorylation (Ser15) and increased protein expression of p53 and MDM2, in purified patient MM cells. Pat indicates patient. (D) Localization of p-p53, p53, and MDM2 proteins in cytoplasmic and nuclear fractions of MM.1S cells treated with PS-341. Anti–α-tubulin and anti–nucleolin antibodies are used to confirm equal loading of cytoplasmic and nuclear proteins, respectively. (E) Coimmunoprecipitation of p53 and MDM2 in MM.1S cells treated with PS-341.