GREB1 and neoplasm: Strikingly, investigation of the DSCAM-AS1 promoter revealed that ER preferentially binds to the DSCAM-AS1 promoter in tumours with clinical aggression (ie, metastatic and tamoxifen non-responders; Fig. 5d), while a canonical ER target, GREB1, exhibits ER-biding to its promoter in nearly all ER-positive tumours, lacking preference for the more clinically aggressive tumours.