FIGURE 4.

A, integrin endocytosis assay to examine the recycling α6 integrin. BV2 and iPLA-KD cells were plated on LN-coated coverslips, and an integrin endocytosis assay was performed as described under “Experimental Procedures.” In untreated BV2 and iPLA-KD cells, endocytosed α6 integrin was found predominantly in a perinuclear vesicular structure. Following ADP treatment, α6 integrin localization changed to plasma membrane or vesicles in the periphery of BV2 cells, but this change is absent in iPLA-KD cells. Scale bar, 10 μm. The ratios of fluorescence intensities in the perinuclear area and cellular periphery from 10 cells were determined and are shown in the graph. Error bars represent S.E. **, p < 0.01 versus BV2 by ANOVA. B, endocytosed α6 integrin is colocalized with mCherry-Rab11 in the perinuclear region, but the localization of α6 integrin changes rapidly to the periphery of the cell upon ADP stimulation. However, in iPLA₂-KD or BEL-treated BV2 cells, α6 integrin remains colocalized with Rab11 in the perinuclear region even after ADP stimulation.