CDCP1 is required for invadopodia formation and ECM degradation by human breast cancer cells. CDCP1 is required for invadopodia formation and ECM degradation by human breast cancer cells. A, the MDA-MB-231 cells were treated with control or CDCP1 siRNAs and subjected to Western blotting with the indicated antibodies. The black arrowhead shows CDCP1. B, the cells treated with the indicated siRNAs were cultured on fluorescent gelatin-coated coverslips for 7 hours and stained for F-actin. C, the areas showing degradation of the fluorescent gelatin matrix were quantified as described in the Materials and Methods. D, the proportion of the cells showing degradation of the gelatin matrix. E, the relative number of invadopodia per cell. F, the result of the invasion assay of the MDA-MB-231 cells treated with CDCP1 siRNAs. Columns, mean; bars, SD. *, P < 0.05. Yuri Miyazawa et al. Mol Cancer Res 2013;11:628-637 ©2013 by American Association for Cancer Research