Cell lines established from (BALB/cx DBA/2)F1 mice which show parent type susceptibility to murine leukemia viruses

The susceptibility to two tissue culture cell lines established from (BALB/cx DBA/2)F1 (CDF1) mice to murine leukemia viruses (MLVs) was compared with those of various cell lines. While embryo cells of CDF1 mice were resistant to both N- and B- tropic MLVs, one cell line was susceptible to N-tropic MLV and the other to B-tropic MLV. So the cell lines of CDF1 mice had not the same susceptibility to MLVs as CDF1 embryo cells had. Cell lines established from N- and B-type inbred mice had kept their original susceptibility to MLVs. These results suggested the phenotype of some F1 hybrid mouse cells tended to change into either parental type after establishment as cell lines.