because xeroderma pigmentosum patients have a hereditary predisposition to uv-induced cancer and the cells of such patients are abnormally sensitive to the cytotoxic and mutagenic effects of uv radiation , we compared fibroblasts from 6 bilateral rb patients and 3 normal individuals for their sensitivity to the mutagenic effects of cobalt 60 , using resistance to 6-thioguanine ( tg ) as the genetic marker .
C0007634
the cells
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fibroblasts