Fig. 4

The influence of melanoma cells on the proteolytic activity of fibroblasts. CAFs obtained using melanoma-conditioned media (CM) and melanoma cells on Transwell inserts (INS) were seeded on coverslips coated with gelatin-FITC (green). Control (CTRL) constitutes of fibroblasts cultured in FBM:DMEM (1:1 ratio) analogous to tested cells. A After 8 h of incubation, cells were fixed and stained using phalloidin to visualize F-actin, which then were used to create a cell mask. Areas of gelatin degradation are visible as dark holes on a green background. Scale bar—25 µm. B Digestion areas were determined in Fiji software. F-actin staining was used to create a cell mask and determine its area. Asterisks indicate statistically important differences between control cells and CAFs or between different types of CAFs. The significance level was set at p ≤ 0.05 (*), p ≤ 0.01 (**), p ≤ 0.001 (***), and p ≤ 0.0001 (****)