| High rate of CAD gene amplification in human cells deficient in MLH 1 or MSH 6 . ^^^ We show here that the rate of CAD ( carbamyl P synthetase / aspartate transcarbamylase / dihydroorotase ) gene amplification is elevated 50 to 100 fold in human cell lines deficient in MLH 1 or MSH 6 , as compared with mismatch repair proficient control cells . ^^^ |