CTGF/CCN2 contributes to the stabilization of surface-level integrin complexes. (A) HC11-TRE and HC11-TRE-CTGF cells were incubated in serum-free media with EGF (10 ng/ml) or identical media containing either an RGD-containing peptide or RAD-containing peptide (500 μM). The MTT assay was performed at 24, 48, 72, and 96 hours. The results are displayed as the mean + the S.D. of four determinations. *, p < 0.005. (B) HC11-TRE and HC11-TRE-CTGF cells were grown in serum free media for 4 days in the presence of EGF (10 ng/ml). Cells were harvested and stained with an anti-β1 integrin antibody, anti-α6 antibody or isotype controls followed by detection with a fluorescence-conjugated secondary antibody and analysis by flow cytometry. The median number of β1 integrin or α6 positive cells is indicated. The data are representative of 4 independent experiments.