Figure 3From: Collagen density promotes mammary tumor initiation and progression Increased metastasis associated with dense stromal collagen. (a) Increased number of lung metastases per lung at 15 weeks in mice that formed tumors in collagen-dense mammary glands (PyVT/Col1a1) when compared with mice that formed tumors in control glands (PyVT/wt; mean ± standard error of the mean (SEM), n = 4 of each genotype). (b) Three-dimensional tumor cell invasion assay showing that tumor explants from collagen-dense tumors (PyVT/Col1a1) resulted in more invasion into three-dimensional collagen gels and colony formation after 10 days than explants from PyVT/wt tumors (mean ± SEM; n = 4 PyVT/wt and n = 14 PyVT/Col1a1 tumor explants from four sibling mice). (c) Tumor cells extracted from collagen-dense tumors (PyVT/Col1a1) showed increased migration when compared to tumor cells from control tumors (PyVT/wt) as measured by transwell migration assays with serum as the chemoattractant (mean ± SEM; n ≥ 3 independent experiments). *Indicates a statistically significant difference (p < 0.05) following analysis with t-tests.Back to article page