Co-immunoprecipitations were conducted according to the protocol in [77 (link)]. Briefly, the protein concentration of E−Du145 and E−PC3 lysates were determined by Lowry assay (Biorad Dc assay cat: 500, Biorad, UK). Aliquots of cell lysates containing 500 μg protein were transferred to new tubes and the volume adjusted to 400 μL with lysis buffer. 30 μL packed Pierce Protein A/G Plus Agarose Beads (Life Technologies #20423) were combined with 500 μg whole cell lysate on a rocker at 4 °C for 1 h to clear the lysate. 500 μg cleared protein lysate and 5 μg/mL primary antibody were rocked overnight at 4 °C. Control samples had 5 μg isotype-matched control IgG added. 30 μL of fresh packed beads were added to the protein lysate with primary antibody and rocked at 4 °C for 1 h. Samples were centrifuged for 5 min at 10,000 × g. The beads were washed three times with 500 μL immunoprecipitation buffer (20 mM Tris, 100 mM NaCl, 1 mM EDTA, 1% Tween) before applying 25 μL 2× SDS sample buffer (Bio-Rad 161–0737) with 10% β-mercaptoethanol (Sigma-Aldrich M6250) and boiled at 100 °C for 5 min. The samples were centrifuged briefly at room temperature before loading with Prot/Elec tips (Bio-Rad 2239916) on a western blot.