In keeping with previous findings,23 all wt ER+ breast cancer cell lines tested showed a concentration-dependent increase in proliferation in response to abiraterone (wt-MCF7 EC50 2.76 μM (95% CI 2.60–2.94 μM); wt-SUM44 EC50 1.56 μM (95% CI 1.4–1.72 μM); wt HCC1428 EC50 2.06 μM (95% CI 1.81–2.32 μM)) (Fig. 1a). Here, ESR1 is linked to breast carcinoma.