121°C for 15 min in 10 mM citrate buffer solution (pH 7.0) for antigen retrieval, and endogenous peroxidase activity was then blocked with 3% H2O2 solution. The sections were incubated with anti-RhoB and anti-RhoC polyclonal antibodies for 1 hr at room temperature (RT) and then incubated with peroxidase-conjugated dextran polymer anti-rabbit antibody for 30 min at RT. After incubation, they were visualized with 3,3' diaminobenzidine. Results: RhoB protein was found in the nuclei of both normal oral epithelial cells and cancer cells. Although RhoB was positive in all 18 specimes (100%) of OSCC without metastasis, it was negative in 6 (67.7%) of the 18 with metastasis
(p < 0.05). RhoC was positive in only one of the 18 OSCC with metastasis. Conclusion: The results suggest that RhoB negativity is associated with potential to metastasize to the lymph nodes.