TIPARP and breast carcinoma: Estradiol induces the expression of TIPARP in breast cancer cells via ER-α, TIPARP is a negative feedback regulator of ER-α that inhibits the transcriptional activity and expression of ER-α in breast cancer cells and reduces its recruitment to target genes, and TIPARP knockdown increases the transcriptional activity and expression of ER-α to promote estradiol-induced cell proliferation [48].