Abstract: The present invention provides a novel method for detecting the presence, or absence, or reduced level of an mRNA transcript of a novel tumor suppressor gene, hereinafter referred to as the "CATR1 gene". The method comprises isolating mRNA from tissue samples, amplifying the mRNA by reverse transcriptase-PCR using primers specific to a region in the CATR1 gene, and detecting the presence or absence of the amplified product to determine whether CATR1 mRNA is present or absent or present at reduced levels in the tissue sample. Optionally, the CATR1 mRNA when present, is also quantified. The present invention also relates to the primers which are used in the method. The present invention also relates to a segment of the CATR1 gene, hereinafter referred to as the "CATR 1.3 genetic element," which is useful for designing the primers used in the method of detecting CATR1 mRNA. The CATR 1.3 genetic element is also useful for preparing antisense nucleic acid segments which are CATR1 gene specific inhibitors.