APN/CD13 expression in OVCA tissues A, B, C, D and E; Immunohistological staining of APN/CD13 in surgically resected OVCA tissues of 14 patients representing four different histological types using APN/CD13 specific Ab. A-D; APN/CD13 was expressed intensely in tumor cells but only slightly in stromal cells. A; clear cell carcinoma (case 7), B; endometrioid adenocarcinoma (case 8), C; mucinous cystadenocarcinoma (case 5), D; serous cystadenocarcinoma (case 12), E; serous cystadenocarcinoma (case 2), APN/CD13 was intensely expressed in stromal cells but was almost undetectable in tumor cells. F; APN/CD13-negative control of serous cystadenocarcinoma. Black arrows indicate tumor cells expressing APN/CD13; green arrows indicate stromal cells expressing APN/CD13.