Effects of Spalax and mouse fibroblasts on growth of co-cultured human hepatoma cells. Tumor cells (TC) were cultured either alone or in the presence of Spalax or mouse fibroblasts in the ratio of 1:10 (5 × 104 fibroblasts and 5 × 103 cancer cells in six-well plates) in RPMI/DMEM-F12 media (1:1) containing 10% FBS. White arrows point to the foci of destroyed cancer cells, and black arrows show the fibroblast-tumor cell colony boundaries. Cells in mono- and co-cultures were observed and photographed daily. Representative images for each sample at different time intervals are shown (×200).