ESR1 and osteosarcoma: In an ER-CALUX assay using human osteosarcoma U2OS cells stably transfected with ERα and transiently transfected with ERβ, AIF stimulated the endogenous ER-estrogen response element (ERE) interaction and, thus, the luciferase reporter gene activity (Djiogue et al., 2009; Magne Nde et al., 2012).