Figure 4: Induced circular ruffles are enriched with phosphorylated PDGF β-receptors. Cells were stained for phospho-PDGF β-receptors (Y1009) (green) and F-actin (red). Serum-starved cells exhibit no ruffles or lamella (b) and exhibit some staining for the phosphorylated PDGF β-receptor (a). Upon stimulation with PDGF-BB, circular ruffles are formed as detected by labeling for F-actin ((e), (h), arrow). The phosphorylated PDGF β-receptor is abundant in the newly formed circular ruffles ((d), (g), arrow). Next to circular ruffles, also edge ruffles and lamella are formed upon stimulation with PDGF-BB ((h), arrow). The phosphorylated PDGF β-receptors also co-localize in these newly formed F-actin structures ((g), (i)). Bar represents 10 μm.