ESR1 and ductal breast carcinoma in situ: In the present study, we compared the effect of OA on proliferation and migration in two human DCIS cell lines, MCF10DCIS.COM (estrogen receptor; ER, progesterone receptor; PR and HER2-negative) and SUM-225 (HER2 overexpressed) cells, and investigated the different action of OA on the cellular behavior of the distinct subpopulations (ALDHhigh and ALDHlow) isolated from MCF10DCIS.COM cells.