We have developed a general PCR-based method to quantify the amount of a specific mRNA present in a given cell line or tissue. We applied this quantitative PCR to analyse the expression of D8, a human gene which we recently identified in the chromosomal region 3p21, the common deletion region of lung cancer. Our PCR-aided assay shows that in most lung-cancer-derived cell lines the amount of D8 transcripts is only 2% or less of that in normal lung tissue. The virtual absence of expression may imply some role of the gene in the development of lung cancer.