A purified anti-cancer peptide consisting of amino acids 266 to 287 of Genbank Accession No. O68604 (SEQ ID No. 4), and modified and homologous forms of the peptide are described. The modified or and homologous forms of the peptide include more than contiguous amino acids having at least 75% amino acid sequence identity with at least 8 contiguous amino acids of amino acids 266-287 of Genbank Accession No. O68604 (SEQ ID No. 4) defining a motif selected from the group consisting of RRRVQQ (SEQ ID No. 5) and RGRAK (SEQ ID No. 1). The peptide(s) can be produced by B. linens, a Brevibacterium commonly used in the production of cheese. There is also provided method for prophylaxis or treatment of cancer in a mammal, comprising treating the mammal with an effective amount of the peptide, or a protein the pepsin cleavage of which yields the peptide.
