(A and B) Cell proliferation (A) on plastic or (B) on Col1. n = 5. **P < 0.01; ***P < 0.001. (C–E) 344SQ transfectants were coinjected with 5% Matrigel, 5% Col1, or phosphate-buffered saline, and (C) tumor volumes were measured weekly. (D and E) Primary flank tumor weight and number of lung metastases in each mouse were measured and quantified at necropsy. n = 5. Scale bar: 1 cm. *P < 0.05; **P = 0.001; ***P < 0.001. (F) 344SQ cells were transfected with siRNA targeting the 3′ untranslated region of Itga1 mRNA (siUTR) or control siRNA (siCTL) and Itga1 expression vector or empty vector, and the transfectants were subjected to Boyden chamber Matrigel and Col1 invasion assays. Invaded cells were quantified. (G) Bright-field micrograph of a 393P_ZEB1 spheroid in Col1 showing cells invading singly or collectively. Invading single cells per sphere were quantified (graph). Scale bar: 100 μm. (H) Time-lapse tracing of movements of 344SQ cell transfectants on Col1. Movements of individual cells over 6 hours are indicated by colored lines. Bar graphs show the quantification of cell speed and directionality. (I) Confocal micrographs of focal adhesions (tyrosine 118 phosphorylated paxillin (pPXN [Y118]), green) and nuclei (DAPI, blue) in 344SQ cell transfectants. Scale bar: 10 μm. The scatter plots show the number of focal adhesions (FA) and area of FA in each cell (dots). Data are shown as the mean ± SEM from a single experiment incorporating biological replicate samples (n = 3, unless otherwise indicated) and are representative of at least 2 independent experiments. Two-tailed Student’s t test for 2-group comparisons; 1-way ANOVA test for multiple comparisons.