DHTKD1 and colorectal cancer: The Ad·(ST13)·CEA·E1A(Δ24) vector was successfully constructed by replacing the native E1A promoter with the colorectal cancer-specific CEA promoter, deleting 24 bp in Ad·E1A (923–946 bp) and harboring the antitumor ST13 gene, as shown in Fig. 1A.