ESR1 and prostate cancer: When we checked the ERα, ERβ and AR status in different prostate cancer cells as well as in a benign prostatic hyperplasia cell line (BPH-1), we detected ERα protein in some prostate cancer cells and ERβ protein in all cell lines (Figure 1A and supplementary Figure 1A) even though ERα mRNA was detected in all the cells tested (Figure 1B).