S-phase delay in human hepatocellular carcinoma cells induced by overexpression of integrin β1

Figure 1 Integrin α5 and β1 protein levels in α5-, β1- and α5β1 transfected SMMC-7721 cells. (A) The expression level of α5 chain was increased in α5-7721 and α5β1-7721 cells. (B) Two forms of β1 integrin were due to different levels of β1-chain glycosylation. The hypoglycosylated lower band was tenta-tively identified as biosynthetic precursor of β1 subunit, the hyperglycosylated upper band was mature subunits, exposed in part on the cell surface (the 130-kDa product). Immunoblot assay showed that protein levels of the mature form were el-evated in the transfectants, especially in β1-7721 and α5β1-7721 cells. (C) The protein level of β-actin showed an equal loading amount in each well. Lane 1, mock cells; lane 2, α5-7721; lane 3, β1-7721; lane 4, α5β1-7721. Each point in the graphs was the mean value from three separate experiments.