FIG. 5.

Southern blot analysis of tumor DNA to detect the presence of recombinant MCF virus. DNA from 10 MoFe2-MuLV-induced tumors and from an uninfected (uninf.) NIH-Swiss mouse was digested with BamHI and ClaI and hybridized to a 1.1-kb BamHI-ClaI fragment of the Mo-MuLV env gene as previously described (5). The 1.1-kb fragment generated from the ecotropic MoFe2-MuLV env gene, the 1.9-kb fragment diagnostic of MCF proviral DNA (arrows), the identifying number of each animal, and the latency of tumor induction (in weeks postinoculation [p.i.]) are indicated.