ESR1 and breast carcinoma: In vitro, the loss of viability upon EDI3 silencing was found to be more pronounced in ER-HER2+ SKBR3 and HCC1954 cells compared to cells that are ER + HER2 + (BT474 and EFM192A) [6], suggesting that EDI3 may have specific roles in the different breast cancer subtypes.