Using this model of GFP-LIMK1 targeted to distinct subcellular compartments in MDA-MB-231 breast cancer cells, we found that both nuclear- and cytoplasmic-targeted GFP-LIMK1 enhanced FAK/paxillin/Src/AKT/Erk signaling, increased cellular invasion, and promoted xenograft tumor growth in nude mice. This evidence concerns the gene PTK2 and breast cancer.