Overexpression of beta1-integrin in cultured cells.

(A) CLSM image of an A4-HeLa cell transfected with the beta1 integrin-ECFP construct. The fluorescent protein signal could be detected homogeneously distributed in the cytoplasm. When A4-HeLa were transfected with beta1 integrin-ECFP and alpha6 integrin expression vectors and plated on laminin-coated coverslips, membrane structures could only be identified in cells with low expression levels of ECFP signal. (B) Western blot of MCF7 cells stably-transfected with a beta1 integrin expression vector. Cells expressing exogenous beta1 integrin show higher levels of the low molecular weight band of beta1 integrin. (C) Plasmid map of beta1 integrin-ECFP shRNA 3’UTR. This construct has the coding sequence of beta1 integrin-ECFP followed by an IRES sequence and a shRNA targeted to the 3’UTR of murine beta1 integrin mRNA. This plasmid allows us to simultaneously diminish the endogenous levels of beta1 integrin while the fusion protein is overexpressed.