CEACAM5 and colonic neoplasm: To further confirm if the antitumor effect of Ad (ST13)·CEA·E1A(Δ24) was CEA-specific or colon-specific, we compared its effect on CEA-negative colon cancer cell line (Colo-320) and CEA-positive non-colon cancer cell line (A549, MCF-7), as shown in Fig. 3C.