CCN1 and breast carcinoma: A recent investigation in estradiol-sensitive breast cancer cell lines resistant to 4-hydroxytamoxifen (4-OHT), the major metabolite derived from tamoxifen, showed that silencing of Cysteine-Rich Angiogenic Inducer 61 (CYR61) expression resulted in a significant decrease in cell invasion and re-sensitization to 4-OHT, suggesting that CYR61 suppression could be a promising therapeutic strategy to improve the treatment of tamoxifen-resistant breast cancer (24).