To examine the interaction between CRC-/CSC-cells and fibroblasts and to evaluate the effect of curcumin and/or 5-FU on this synergistic crosstalk, on tumor cell proliferation, invasion and tumor-promoting factors (MMPs, NF-κB) expression in more detail, we performed western blotting analysis of the high density tumor microenvironment co-cultures. This evidence concerns the gene NFKB1 and colorectal carcinoma.