STK11 and cancer: In MDA–MB-435 breast cancer cells without LKB1 expression, over-expression of wild-type LKB1 can significantly inhibit the invasion and metastasis of cancer cells in vitro and in vivo, and this is accompanied with downregulation of matrix metalloproteinase 2 and 9 (MMP-2 and MMP-9) as well as vascular endothelial growth factor (VEGF) [115].