ESR1 and breast carcinoma: Resistance to therapies for ER+ breast cancer and enhanced survival of disseminated MCF7 cells stably expressing GIV recapitulate key features of MCF7 cells in co-culture with MSCs that we reported previously (19, 21), and future studies will delineate whether and how GIV alone may impact additional reported phenotypes, i.e., metabolic plasticity (20).