FIG. 3.

Southern blot analysis of genomic DNA from clone A405 and its G418^r/Gan^r subclones FS-3 and FS-4. Genomic DNA was digested with either SspI or EcoRI and separated by standard agarose gel electrophoresis. Hybridization was performed with the pNTP-Δ plasmid as a probe. The lighter bands that are the same size in all three cell lines are due to cross-hybridization of the probe with the mouse endogenous pgk promoter. The location of DNA size markers and the limit of resolution (LOR) are shown.