Firstly, we asked whether NHE1 plays different roles on Etoposide-mediated apoptosis in mammary cancer cell lines (MCF7 and MDA-MB-231), BCR-ABL− hematopoietic cell lines (HL-60 and Jurkat), and BCR-ABL+ hematopoietic cell line (K562). This evidence concerns the gene SLC9A1 and breast cancer.