FIG. 3.

Confirmation of the correct Env DNAs in tumor-bearing mice. DNA samples were extracted from lungs of the indicated mice and were subjected to PCR amplification using nested primers flanking the Env cDNA. The expected 1.8-kb products were obtained for all mice that received Env expression vectors (not shown). These DNA fragments were then cut with PstI and PvuII restriction enzymes and were subjected to gel electrophoresis to determine the origin of the DNAs. The expected Env and the expected sizes of the restriction fragments are indicated below the gel picture.