分子生物学家发现一些关键性基因,受损时能引起肺癌。荷兰及英国的科学家发现,各种类型的肺癌细胞都缺少一段DNA。这一发现进一步证明,在一对“肿瘤抑制”基因机能失常或缺失时就会发生某些类型的癌。这一对基因可能产生某种控制细胞生长的化学物质。如果吸烟引起这些基因中的一个基因(等位基因)发生一个小“点”突变,细胞就进入癌前状态。其他染色体上仍有功能的等位基因的产物足以阻止发展为成熟的癌。如果在第二个等位基因上发生某种情况(如在细胞分裂时丢失该等位基因), Molecular biologists have discovered that some key genes can cause lung cancer when damaged. Scientists in the Netherlands and the United Kingdom have found that all types of lung cancer cells lack DNA. This finding further proves that certain types of cancer can occur when a pair of “tumor suppressor” genes malfunction or are missing. This pair of genes may produce some sort of chemical that controls cell growth. If smoking causes a small “dot” mutation in one of these genes (alleles), the cell enters a precancerous state. The products of functional alleles on other chromosomes are sufficient to prevent the development of mature cancers. If something happens on the second allele (such as the loss of the allele during cell division),