The present invention provides a method for inhibiting cell proliferation in a cell comprising contacting the cell with a nucleic acid sequence or a polypeptide having essentially the sequence of the .beta..sub.1C integrin. Also included in the invention are peptides consisting of amino acid residues which are the size of or fewer than the sequence of the cytoplasmic domain of the .beta..sub.1C integrin consisting essentially of the amino acid sequence of SEQ ID NO:1 and SEQ ID NO:2, and functional fragments thereof which are useful for inhibiting cellular proliferation. Peptides, polynucleotides, and antibodies immunoreactive with the peptides, and methods of use for inhibiting cell growth are also provided.