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. Author manuscript; available in PMC: 2016 Nov 16.
Published in final edited form as: Oncogene. 2016 Apr 25;35(45):5860–5871. doi: 10.1038/onc.2016.121

Figure 9. Graphical abstract.

Figure 9

Stressful conditions of the tumour microenvironment activate an adaptive mechanism called the unfolded protein response (UPR). X-box binding protein-1 (XBP1) is a critical transcriptional activator that is induced by the UPR. In estrogen receptor-positive (ER+) breast cancer cells XBP1 is rapidly induced in response to E2-stimulation. In luminal breast cancers estrogen signalling and UPR induce the expression of XBP1s. Here we show that XBP1s upregulates the transcriptional activation of NCOA3 during estrogen signalling and UPR. NCOA3 is required for the induction of estrogen-responsive and PERK-ATF4-responsive genes. Our results suggest that XBP1s regulates growth and proliferation of ER-positive breast cancer cells, in part, by transcriptional activation of NCOA3.