STAT3 and breast carcinoma: On the contrary, another study demonstrated that SIRT4 overexpression downregulates IL-6 expression and STAT3 Y705 phosphorylation, as well as the transcription and translation of STAT3 target genes (MYC and CNDD1), to enhance the sensitivity of MCF7 and T47D breast cancer cells to tamoxifen, thus potentiating the effect of this chemotherapy against breast cancer cells [72].