Relationship between fibroblast invasion-promoting capacity and donor type. Conditioned media (CM) (i) and fibroblast co-culture (ii) invasion assays were carried out comparing eight normal donors and eight tumor donors. Graphs (a) and (c) show scatterplots of individual donors, and (b) and (d) illustrate mean invasion generated by the two donor groups. In the CM assay, significantly higher levels of tumor invasion were generated by CM from tumor-derived fibroblasts compared with normal fibroblasts (b) (p = 0.009). Higher levels of invasion were generated in the fibroblast co-culture assays compared with the CM assay for both normal (p ≤ 0.001) and tumor-derived (p = 0.02) fibroblasts (b,d), and a significant difference between normal and tumor-derived fibroblast invasion-promoting capacity was demonstrated in the co-culture assay (d) (p = 0.039). * p =< 0.05.