To investigate whether AR activation altered the GATA3 cistrome in a more clinically relevant context, we performed GATA3 ChIP-seq in bio-banked tumors from an AR+/GATA3+ patient-derived xenograft (PDX) model of ER+ breast cancer (GAR15-13D) treated for 5 days in vivo with a vehicle control or a selective AR modulator (SARM; enobosarm) that has AR agonist activity in ER+ breast cancer cells (Additional file 2: Fig. S2D-E) [8]. This evidence concerns the gene ESR1 and breast cancer.