the dna alkylating agent 4-nitroquinoline-1-oxide , which creates dna base adducts that are slowly removed from mammalian cell dna , induced no detectable dna repair in hepatocytes up to a toxic dose level of 2 x 10 ( -5 ) m with the 4 hour exposure period , whereas a marked dna repair response was observed at 10 ( -5 ) m when the 18-20 hour exposure/labeling period was used .
C0242958
dna
C0012854
dna