Generation of CT26 cell lines producing excess, endogenous, or decreased TGF-β.
A CT26 colon cancer cell line was genetically engineered (see Methods) to express TGF-β (CT26-TGF-β) or TGF-β dominant-negative receptor (CT26-TGF-β-R). Neomycin empty cassette was used to generate the control cell line, CT26-neo. A) Schematic representation of the in vitro experiments performed. B) The concentration of the active form (acidified) of TGF-β present in the tumor cell culture media measured by ELISA. C) The concentration of TGF-β-R in the tumor culture media measured by ELISA.