Immunohistological analysis of tumors. Immunohistochemistry on tumors from vehicle- (A, C, E) and α-methyl dopa-treated mice was performed using specific antibodies against CK-19 (A, B), dopamine (C, D) and PCNA (E, F). Representative photomicrographs of the immunoreactivity are shown (magnification X40). Semi-quantitative analysis of PCNA immunoreactivity was performed and data was expressed as average (± SEM) PCNA positive nuclei per field (G) and the asterisk denotes significance (p<0.05) compared to vehicle-treated tumors. PCNA expression in the tumors was also assessed by real time PCR (H). Data are expressed as average ± SEM (n=3). Asterisk denotes significance (p<0.05) compared to vehicle-treated tumors.