Abstract: An isolated nucleic acid encodes a polypeptide for inhibiting growth of a cancer cell. The amino acid sequence defines a binding domain of a ? integrin subunit for ERK2 MAP kinase, the binding domain comprising an intervening, centrally located amino acid linker sequence that links opposite terminal end amino acid sequence regions of the binding domain together and is non-essential for binding of the MAP kinase to the binding domain. The linker sequence of the binding domain is deleted such that the opposite terminal end amino acid sequence regions of the binding domain remain and are contiguous with one another. Also provided are vectors incorporating the nucleic acid and methods for prophylaxis or treatment of cancer in a mammal, comprising administering the nucleic acid for expression of the polypeptide encoded by the nucleic acid in the cancer cells of the cancer.