To further determine whether LKB1 expression is associated with metastatic progression of breast cancer, we examined the expression levels of LKB1 in immortalized breast epithelial cell line MCF-10A and breast cancer cell lines, including luminal A subtype (MCF-7 and T47D), luminal B subtype BT474, and metastatic SKBR3 and MDA-MB-435 s. This evidence concerns the gene STK11 and breast cancer.