ESR1 and cancer: From these hybrids, bromo substituted compounds, 38 and 39 were found to be most effective in targeting ER-α. RT-PCR and Western blotting experiments results showed that both the hybrid compounds 38 and 39 altered the mRNA and ER-α receptor protein expression, thus preventing the further transcriptional activation and signaling pathway in cancer cell line (Table 13, Figs. 28 and 29).