ESR1 and cancer: This study aims to gain a better understanding of therelationship between CCN5 and ER-α in normal and cancer cells, the molecularbasis of restoring ER-α by CCN5 in TNBC cells, and finally, the efficacy oftamoxifen (Tam) in TNBC cells by combination treatment of Tam and human recombinantCCN5 (hrCCN5) protein using rational in vitro and in vivomodels.