To elucidate cellular changes that accompany the development of resistance to FOXM1 inhibition, we compared WT parental breast cancer cells sensitive to suppression of cell viability by FOXM1 inhibitor with cells that acquired resistance to FOXM1 inhibitor NB73 by long-term (> 6 months) treatment with the drug, as reported previously [13]. This evidence concerns the gene FOXM1 and breast cancer.