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与某些肿瘤有关的正常人基因改变的根据虽然已无可辩驳,但对这些所谓“细咆致癌基因”的全部研究,几乎都是应用实验室培养的细胞系。最近,美国研究人员首次检查了新切除的人肿瘤中致癌基因的表达。他们在多种肿瘤中发现病毒致癌基因的细胞相应物,这是哺乳动物中首次发现的细胞相应物。而且,这一结果支持了最新的假设,即如果肿瘤一旦发生,一定有一种以上的致癌基因被激活。虽然细胞培养提供很多有价值的资料,但在用于研究最复杂的生物学过程中,充其量只是一种人工方法。在长期生存的细胞株中,DNA的量和表达率通常经过很大的改变。而且相当于每种癌瘤的这些细胞系并不很多。
Although the basis for genetic alterations in normal humans associated with certain tumors is irrefutable, almost all of these so-called “fine-cut oncogenes” have been studied using laboratory-cultured cell lines. Recently, American researchers first examined the expression of oncogenes in newly resected human tumors. They found cellular counterparts of viral oncogenes in a variety of tumors, the first cellular counterparts found in mammals. Moreover, this result supports the latest hypothesis that if tumors occur, there must be more than one oncogene activated. Although cell culture provides valuable information, it is at best an artificial method for studying the most complex biological processes. In long-lived cell lines, the amount of DNA and the rate of expression are often greatly altered. And there aren’t many of these cell lines that are equivalent to each type of cancer.