BCL2L11 and breast cancer: To test the association of Hsp70-Bim PPI with the survival of tamoxifen-resistant breast cancer cells, gradient tamoxifen-resistant MCF-7 cell lines were established that adapted for growth in the presence of 1 μM and 3 μM tamoxifen, respectively and named as MCF-7/R1 and MCF-7/R2.