Objective:To examine NJ001 recognized antigen expression in surgically resected human malignant tumor tissues,and to evaluate the relationship between its expression and tumor differentiation. Methods:NJ001 recognized antigen expression was immunohistochemically studied in lung adenocarcinoma,lung squamous carcinoma,pancreatic cancer,breast cancer,esophageal cancer,gastric cancer,liver cancer and matched non-neoplastic tissues,and all positive cases were compared on tumor differentiation. The results were scored by semiquantitative analysis,and statistical analysis was evaluated by chi-square test or Fisher exact test. Results:Expression of NJ001 recognized antigen was significantly high in lung adenocarcinoma (88.0%),lung squamous carcinoma(82.2%),pancreatic cancer(73.3%)and breast cancer(57.8%),and was significantly correlated with lower differentiation degree in all these tumors (P < 0.001 in lung adenocarcinoma;P=0.002 in lung squamous carcinoma;P=0.002 in pancreatic cancer;and P=0.024 in breast cancer). Conclusion:NJ001 recognized antigen is expected to be a tumor marker in lung adenocarcinoma,lung squamous carcinoma,breast cancer and pancreatic cancer,as well as a remarkable biomarker for identification of differentiation degree in multiple neoplasms.