Table 1.

Allele-specific PCR analysis of Aprt mutant clones

	Total no. of clones	No. of clones lacking the nontargeted Aprt allele	LOH*, %
Background†	140	97	69
DMBA	92	64	70
ENU	125	13	10
x-rays	43	30	70

^*Loss of heterozygosity. 

^†Ref. 13.