FIGURE 1.

Abl kinases are required for invasion and MMP-dependent matrix degradation. A, MDA-MB-231, MDA1833, a derivative that metastasizes to the bone, and MDA4175, a derivative that metastasizes to the lung, were transduced with the indicated lentiviral miRNAs, sorted, and plated on the upper wells of matrigel invasion assay chambers in serum-free medium. Invasion toward serum-containing medium was analyzed after 48 h. Cells on the undersurface of the matrigel membrane were stained and quantified below as mean ± S.E. B, cells transduced with lentiviral miRNAs for control or Abl+Arg miRNAs, were sorted and plated on coverslips coated with OregonGreen-conjugated gelatin for 6 h. Cells were fixed and nuclei stained with Hoechst (blue). Areas of gelatin degradation (black area) were quantified as mean ± S.E. Experiments are quantified from five randomly selected fields under a 20× objective. Data are representative of at least three independent experiments. C, Western blot analysis of lysates from control (C) and Abl/Arg (A/A) knockdown cells with antibodies for Abl, Arg, p-CrkL (Y207), and total CrkL. D, MDA-MB-231 cells expressing either control or Abl/Arg lentiviral microRNAs were retrovirally transduced with miRNA-resistant mouse wild type (WT) Abl and analyzed for invasion and gelatinase activity. Gelatin degradation is quantified as described in Fig. 1B. E, Western blot analysis of knockdown and reconstituted cells with indicated antibodies as above, with tubulin staining used as a loading control. Data are representative of three independent experiments.