ESR1 and breast cancer: FoxO3a-induced up-regulation of integrin α5 is not limited to TamR cells, but it also occurs in parental MCF-7 (Figure 3b,c), in the TamR-derived Tet-inducible stable cell line (Appendix B, Figure A2d,e) and in other ERα+ BC cell lines, T-47D and ZR-75, including their Tam-resistant counterparts, T-47D/TR and ZR-75/TR cells (Appendix B, Figure A2f,g, respectively).