Cells Are Genetically Abnormal

In the previous section we stated that a strong correlation exists between the mutagenic properties of a chemical and its potency as a carcinogen. This is consistent with other evidence that mutation often plays a causal role in carcinogenesis. 

The most graphic illustrations of the correlation between genetic abnormality and cancer come from the 

The first chromosome abnormality found to be associated with a cancer was the Philadelphia chromosome, which arises as a result of a reciprocal translocation between chromosomes 9 and 22 (fig. S4.4). The tumor associated with this translocation is chronic myelogenous leukemia and results from the activation of the c-abl oncogene, which is normally located on chromosome 9. 

Whereas it is a common belief that tumor formation involves mutation, certain properties associated with the etiology of teratocarcinoma do not fit with this concept. Tera- 

AIDS virion structure. Numbers associated with proteins are kilodalton masses (e.g., gpl20 is a 120-kd protein). ( Scientific American, Inc., George V. Kelvin. Reprinted by permission.) 

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Cancerous Cells Are Genetically Abnormal Some Tumors Arise from Genetically Recessive Mutations... 

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