Figure 1. Experimental design of tumorigenesis assay.

(a) Transgenic mice were taken off of doxycycline drinking water at 7–8 weeks of age to induce expression of the human C-MYC transgene specifically in the liver from the LAP promoter, except for one control group (MYC off). Exactly one week after C-MYC induction, all groups except one control group (MYC on, no injection) were given hydrodynamic injections of phosphate-buffered saline alone or DNA plasmids diluted in phosphate-buffered saline. Mice were monitored weekly, imaged every two or three weeks, and sacrificed when tumors were detectable by gross distention of the abdomen as pictured. Inset shows the dissected liver and tumors from the pictured mouse, which was representative of all mice in all groups. (b) The plasmids given by hydrodynamic injection and their features.