Exogenous expression of tensin 1-SH2PTB stabilizes Cas residence at focal adhesions. (A) Representative FRAPs of GFP-tagged Cas expressed in migrating CasKO MEFs co-expressing Cerulean only (top panels) or Cerulean-tensin 1-SH2PTB (bottom panels). Pseudocolor images representing fluorescence intensities of GFP-Cas before (−10 s), immediately (0 s), 15 s, 30 s, 40 s, and 60 s after photobleaching are shown. Scale bar: 1 μm. (B) Mean fluorescence intensities I(t)/I−10 of individual focal adhesions of cells co-expressing Cerulean only (green triangle) or Cerulean-tensin 1-SH2PTB (purple diamond) are plotted against time. (C,D) Mobile fraction, M (C) and half-recovery time, T1/2 (D) were obtained as described in Materials and Methods. Data show the mean±s.e.m.; ***P<0.001; **P<0.01 (n>50 in each group); Student's t-test. Similar results were obtained from three independent experiments. (E) A model for the actin-Cas linkage. Tensin 1 links phosphorylated Cas to inwardly moving actin cytoskeletons at focal adhesions, thereby supporting cell migration.