Figure 3.

β-Casein expression and cell survival in the presence of function-blocking antibodies against β1 and α6 integrins in prerounded cells. SCp2 cells cultured in suspension were treated with prolactin, plus or minus laminin, and function-blocking antibodies against the β1, α6, α1, α5, and αv integrin subunits. (A) Assays of β-casein expression in suspension cultures measure signaling events subsequent to, and independent of, the required cell shape changes. (B) Immunoblots of cell extracts after 3 d of laminin exposure show that laminin-induced β-casein expression in prerounded cells was still inhibited in the presence of β1 and α6 integrin-blocking antibodies. (C) Cell viability was assayed by Alamar Blue dye reduction in duplicate wells under β-casein assay conditions identical to those described for B, but culture was for 4 d (1 d longer) to measure any cell death that may have been initiated during the course of the β-casein assay.