Gene expression analysis after doxorubicin and letrozole treatment on KAIMRC1 cells showed no significant difference when compared to other breast cancer cell lines but treatment with lapatinib showed downregulation of MCL-1 and EGFR genes which correlates with the sensitivity shown by KAIMRC1 cells in the drug sensitivity assay (Fig. 7a). This evidence concerns the gene MCL1 and breast carcinoma.