The target gene C-erbB-2 and control gene thymidine kinase are located on chromosome 17. The different size of two PCR fragments were produced by simulataneously performing PCR on test and control genes in the same PCR mix.

• 靶基因C-erbB-2和对照基因thymidine kinase均定位于17号染色体。 在同一反应体系中进行PCR反应可产生两个大小不同的PCR扩增的特异性片段，然后通过2%25琼脂糖凝胶电泳将两片段分开，再用密度测定仪测定靶基因与对照基因的密度比率，当两者密度比率大于1时，表明存在C-erbB-2原癌基因扩增。