TP53 and neoplasm: Significant brown–yellow signals were detected in the tumor tissue of the EcN (Tum-5), EcN (p53), and EcN (Tum 5-p53) groups, whereas no positive signal was detected in the tumor sections of the PBS and EcN groups (Fig. 6c), indicating that the recombinant protein was continuously and efficiently expressed in the tumor area.