Figure 2. Tumorigenesis after “active” transfection with DNA supernatant of SW480 cells and passive transfection using DNA-depleted supernatant. A.

Agarose gel electrophoresis of DNA extracted from supernatant (Sp), DNA from supernatant treated with DNAse I (Sp+D), protease only (Sp+P), and both (Sp+D+P). DNA is partially degraded by DNAse I and protease, but fully degraded when exposed to both treatments. B. No tumor growth was observed in NIH3T3 exposed to DNA-depleted (DNAse I/Prot) supernatant of SW480 cells, while passively transfected NIH3T3 with untreated supernatant are tumorigenic. +Ctr are SW480 cells and −Ctr are NIH3T3 cells.