ESR1 and breast cancer: In contrast, overexpression of DSCAM-AS1 in T47-D cells, but not MDA-MB-231 cells, led to overexpression of ESR1 (Fig. 3E–H), suggesting that progesterone reduces expression of DSCAM-AS1 that further suppresses expression of ESR1 to inhibit cell migration and invasion in PR-positive breast cancer cells.