ESR2 and neoplasm: However, at the protein level using antibodies directed against the NH2-terminal region of ER-β, detecting both full-length ER-β (ER-β1) and various COOH-terminal truncated isoforms, Fuqua et al (2003) found no correlation between ER-β expression and tumour grade, proliferation, S-phase fraction or DNA ploidy, while others found ER-β status to be a significant predictor of response to endocrine therapy (Mann et al, 2001; Fleming et al, 2004a).