Analysis of histological sections of transfected tumors by the cyclic AMP-responsive element binding (CREB) variants

BNL1ME tumors expressing either one of the specified CREB variants were excised on day 34, and histological sections were microscopically analyzed from random fields (peripheral and central) throughout the whole tumor. Proliferation index figures represent an average number of the cells undergoing division as determined by mitotic nuclei in 10 fields (×100). The sections were stained for apoptosis (terminal deoxynucleotidyl transferase-mediated nick end labeling) and analyzed under a confocal microscope. The number of fluorescent nuclei was determined in 10 fields (×400). The numbers represent the average of apoptotic cells/field. Number of vessels/field was determined from sections stained with an antifactor VIII antibody, an average of six fields was monitored for each tumor (×400). Mean value ± SD and P values are indicated.