Fig. 3. Re-expression of developmentally attenuated genes in human colorectal cancers. (A) Normalization of cDNAs prepared from five of seven independent pairs of tumors (T) and matched normal (N) colonic tissue by RT-PCR analysis of ß-amyloid mRNA, which is known to be expressed to similar levels in cancerous and normal human colon. Labels refer to serial dilution of cDNA before PCR. (B) Expression (RT-PCR) analysis for the seven out of 27 transcripts that show increased expression in two or more of seven T-N pairs, and illustrative results for two transcripts that show minimal change or inconsistent differences between T and N. (C) Results were quantified by gel densitometry, as shown here for one transcript, which encodes a 68 kDa TGF-ß-induced protein. (D) Immunohistochemistry reveals the representative oncofetal marker Trp53 to be expressed in tumor cells and not in the surrounding stroma.