We found in the present study either in monolayer or in high density tumor co-cultures that the intensive crosstalk in the tumor microenvironment co-cultures increased TGF-β3 and p-Smad2 levels in HCT116 cells compared to mono-cultures, indicating active TGF-β signaling in these cells in the tumor microenvironment. The gene discussed is SMAD2; the disease is neoplasm.