Invasive cancer cells form invadopodia on the native BM. (A–C) Localization of invadopodia markers in invasive protrusions: cortactin (A), MT1-MMP (B), and c-src (C). From left to right, columns show actin revealed by phalloidin-Cy3 (red), invadopodia markers as indicated (green), BM detected by immunostaining for laminin and collagen IV (gray), and merged images. Asterisks indicate invasive protrusions. Bars, 5 µm.