FIG. 1.

(A) Southern blot analysis of undigested HPV16 DNA from W12 cells after total DNA extraction. W12 cell DNA was compared to a supercoiled DNA marker (scDNA marker). (B) Southern blot analysis of HPV16 episomes isolated by the Hirt extraction method from W12 and S12 cells and digested with BamHI. (C) Southern blot analysis of HPV16 DNA in W12 and S12 cells. DNA was extracted from 6 × 10⁶ cells, and equal amounts of total DNA were digested with BamHI or PstI and subjected to electrophoresis and hybridization using a ³²P-labeled HPV16 specific DNA probe.