Expression and phosphorylation of ERK1/2 in GC cultured on LN or on plastic substratum. GC were cultured for 24 h on plastic (Pl) or on LN in the presence or absence of anti-α6 IgG (0.5 μg/ml), PD98059 (30 μM) or cytochalasin D (0.5 μg/ml) in culture medium. (a): representative western immunoblotting experiment performed on 10 μg of GC extracts. P-ERK1/2: phosphorylated ERK1/2. (b): ratio P-ERK1/2 / ERK1/2, obtained by quantification of autoradiograms in arbitrary units ; data are expressed as percentages of LN condition (100%, empty bar) and represent mean ± SEM of 6 independent experiments. **: p < 0.01, vs. LN.