XBP1 and breast cancer: Survival analysis using breast cancer data sets by KM plotter revealed that increased expression of XBP1-gene signature was strongly associated with shorter overall survival (OS) (hazard ratio: 2.22, 95% confidence interval: 1.7–2.9, p < 8.3E-9) and relapse free survival (RFS) (hazard ratio: 2.17, 95% confidence interval: 1.9–2.48, p < 1E-16) in ER-positive breast cancer (Fig. 7B).