laminin was present, but treatment with an anti–β1 integrin antibody would prevent expression of the milk protein. Further studies determined that pure laminin-111, but not other ECM components, directs the expression of the β-casein gene through reporter assays (Streuli et al., 1995) and that both α6β4 and β1 integrins are involved (Muschler et al., 1999).
