**3.2 B6 alleles on distal Chr 1 are sufficient to suppress hepatocarcinogenesis on a C3H background**

To determine whether B6 Chromosome 1 alleles can confer resistance to a sensitive C3H background (as C3H alleles confer sensitivity to a resistant B6 background), we generated C3H.B6-Ch1 congenics using ten generations of backcrossing B6 to C3H, selecting B6 alleles on distal Chromosome 1 at each generation. Heterozygous and homozygous congenic males and control inbred C3H males were injected with DEN at 12 days of age and their tumors were counted at 32 weeks (Figure 3). While heterozygosity for B6 alleles had no effect on tumorigenesis (*P*>0.84), homozygosity caused a 3.8-fold reduction in tumor multiplicity (*P*<10-3).
