Detection of the c‐myc Gene Product in Urinary Bladder Cancer

Expression of the c‐myc gene product in urinary bladder cancer was investigated by immunohistochemical staining with anti‐c‐myc monoclonal antibody (mAb) MYC‐1. Positive staining was observed in the cytoplasm, but not in the nucleus in tissues fixed with 10% formalin. On the other hand, positive staining was localized in the nucleus in cryopreserved tissues. Of 34 cryopreserved specimens examined, positive staining with MYC‐1 mAb was observed in 1 of 12 (8.3%) of grade 1 (G1), 12 of 15 (80%) of G2 and 6 of 7 (86%) of G3. Positive staining with Ki‐67 mAb was observed in 2 of 12 (17%) of G1, 12 of 15 (80%) of G2, and 6 of 7 (86%) of G3. These results suggest that tumors with higher nuclear pleomorphism contain more proliferating cells.