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. 2013 Jun 3;4(6):875–883. doi: 10.18632/oncotarget.1036

Figure 3. pRb is necessary for HSP90 protein to protect ESR1 from proteasomal degradation.

Figure 3

(A) Time course analysis of MCF7 cells treated with MG132 for indicated time. After 4 hours, the RB1 kd1 cells expressed the same level of ESR1 as scrambled cells. (B) Analysis as in (A) of three independent experiments utilizing RB1 kd1 and kd2 shRNAs. (C) MCF7 cell lysate untreated (nt) or treated with MG132 for 4 hours was immunoprecipitated with an ESR1 antibody and analyzed by western blot with an anti-ubiquitin antibody. The RB1 kd1 cells showed heavy ubiquitination that extended in the stacking gel. (D) MCF7 cell lysate untreated (nt) or treated with MG132 for 4 hours was immunoprecipitated with ESR1 antibody. In RB1 kd1 cells, there is less HSP90 and p23 proteins bound to the ESR1 protein. HSP70 protein is unaltered. IgG was used as a negative control.