“…(1977), studying F 2 segregants of across between two inbred lines of chickens which differed with respect to MHC antigens, showed that the percentages of animals with terminal sarcomas were, according to B genotype, B 5 /B s (95%), B 2 IB S (26%), and B 2 IB 1 (5%). Schierman et al (1977) showed that regression of Rous sarcoma virus-induced tumors was inherited as a dominant trait coded for by a gene within, or closely linked to, the B region of the MHC. The dominant allele for tumor regression was designated R-Rs-1; the recessive allele for progressive tumor growth in homozygous animals, r-Rs-1.…”