GREB1 and breast cancer: This conclusion is further supported by a patient survival analysis to correlate GREB1 gene expression and relapse free survival for 2898 breast cancer patients (www.kmplot.com) where loss or reduced level of GREB1 is strongly predictive of worse disease outcome for all breast cancer patients in general, and for ER+, and ER+ endocrine treated patients in particular (Figure 2C to 2E).