Figure 1. Schematic presentation of 2 wells from a 12-well culture plate.

On the left-hand side well, fibroblasts were grown alone on a CaF₂ disk. On the right-hand side well, the CaF₂ disk bearing the fibroblasts has been transferred into a well where cancer cells are growing. No direct contact between the two cell types is possible but soluble factors can diffuse through the solution.