ESR1 and breast cancer: The ability of ENDX at 5 μM, but not at 0.01 or 0.10 μM, to block insulin-stimulated AKTSer473 phosphorylation was also observed in the ERα+/HER2- T47D breast cancer cells under serum starved conditions, with TAM and ICI again failing to block insulin-stimulated AKTSer473 phosphorylation (Supplementary Fig. 2b).