Fig. 5

ERα-36 associates with STAT3 and influences STAT3 phosphoryation and acetylation. a, quiescent MDA-MB-231 cells were treated with and without IL-6 for the indicated time periods, and cell extracts were prepared. An equal amount of protein from control and each treatment was immunoprecipitated (IP) using anti-ERα-36 antibodies, and the immunocomplexes were analyzed by Western blotting for STAT3 using its specific antibodies. The blot was re-probed sequentially with anti-pSTAT3, anti-acetyl-STAT3, and anti-ERα-36 antibodies. b, conditions were same as in A except that an equal amount of protein from control and each treatment was analyzed by Western blotting for STAT3 phosphorylation antibodies. The blot was reprobed sequentially with anti-acetyl-STAT3 and anti-STAT3 antibodies. c and d, MDA-MB-231 cells that were transduced with Ad-GFP, Ad-dnSTAT3(c) Ad-dnERα-36(d), after 48 h, cells were treated with and without IL-6 for 1 h, and cell extracts were prepared and analyzed by Western blotting using anti-pSTAT3 and/or anti-acetyl-STAT3 antibodies. The blot was re-probed sequentially with anti-STAT3, anti-GFP, and anti-GAPDH antibodies to show the overexpression of dnSTAT3 or dnERα-36 or for normalization. e and f, MDA-MB-231 cells that were transfected with scrambled or ERα-36 siRNA (100 nM). 48 h after transfection, cells were treated with or without IL-6 for 1 h, and cell extracts were prepared. An equal amount of protein from control and each treatment was immunoprecipitated with anti-STAT3 (e) or anti-ERα-36 (f) antibodies, and the immunocomplexes were analyzed by Western blotting using anti-acetyl-STAT3 antibodies. The blot was re-probed sequentially with anti-pSTAT3, anti-STAT3, and/or anti-ERα-36 antibodies