Flowchart summarizing the analysis of 20 CT candidate genes. Gene expression in normal tissues and cancer cell lines was evaluated by qualitative RT-PCR. Ubiquitous expression corresponds to the presence of PCR products of similar intensity in most or all of the normal tissues examined, as judged by ethidium bromide staining on agarose gels. Variable expression means significant expression in at least several normal tissues, and testis-specific or -predominant expression means significant PCR products were observed only in testis, or in testis and not more than two additional normal tissues (refer to the text and Table 2).