Abstract: Expression cassettes for expression of amphipathic (lytic) peptides in mammalian unicellular (e.g., cultured cells) and multicellular organisms are described, as well as transgenic unicellular and multicellular mammalian organisms having such a cassette stably integrated in their genetic material. In one embodiment, the expression cassette comprises a milk-specific promoter, which for example may be the beta casein promoter, linked in reading frame to control the expression of an amphipathic peptide encoding gene. This expression cassette is useful for production of amphipathic peptides in milk-producing cells and tissues. In another embodiment, the expression cassette comprises an interleukin regulatory sequence adjacently linked to control the expression of an amphipathic peptide encoding gene. The interleukin-regulated cassette is useful to produce disease-resistant animals.