Isolated protein complexes are provided comprising keratinocyte growth factor and vitronectin, or at least domains thereof that enable binding to and activation of both a keratinocyte growth factor receptor and an integrin receptor for vitronectin. These protein complexes include synthetic proteins where the keratinocyte growth factor and vitronectin sequences are joined by a linker sequence. In particular forms, vitronectin sequences do not include a C-terminal heparin binding domain. Also provided are uses of these protein complexes for stimulating or inducing cell migration and/or proliferation in wound healing, tissue engineering, cosmetic and therapeutic treatments such as skin replacement, skin replenishment and treatment of burns where epithelial cell migration is required. In other embodiments, the invention provides inhibition of cancer cell metastasis, particularly in relation to breast cancer.