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. 2013 Jun 1;24(11):1661–1675. doi: 10.1091/mbc.E12-12-0908

FIGURE 4:

FIGURE 4:

β1 integrin is required for Arg-mediated cortactin Y421 phosphorylation at invadopodium precursors in response to EGF stimulation. (A, B) Cortactin Y421 phosphorylation at precursors in the invadopodium precursor formation assay in MDA-MB-231 cells. (A) Representative images of control and β1 integrin siRNA (SMARTpool)–treated cells stimulated with EGF for 0 (untreated) or 3 min and stained with antibodies against cortactin, pY421 cortactin, and phalloidin (F-actin). Insets, Y421 phosphorylation status at cortactin-F-actin–rich invadopodium precursors. Bar, 10 μm. (B) Quantification of pY421 cortactin:total cortactin MFI at invadopodium precursors in cells treated with control or β1 integrin siRNA (left; n > 125 invadopodium precursors; n > 85 cells; three independent experiments) and control and Arg knockdown cells pretreated with IgG, K20, TS2/16, or mAb13 for 10 min before EGF stimulation (right; n > 80 invadopodia; n > 65 cells; three independent experiments). *p < 0.004; **p < 0.026 mAb13 compared with IgG, K20, and TS2/16 and Arg siRNA compared with control siRNA 3 min, IgG, K20, and TS2/16, respectively.