ESR1 and prostate cancer: Moreover, RES modulated the transcriptional activity of the AR in LNCaP prostate cancer cells (Mitchell et al, 1999; Gao et al, 2004), inducing changes in gene expression (Narayanan et al, 2003) that were similar to those observed after inhibiting the transcriptional activity of the ERα in MCF-7 breast tumour cells (Pozo-Guisado et al, 2004).