Table 1.

Tumor induction in hamsters by H19 proviral DNA with adjacent CpG island

Inoculated plasmid*	Frequency of hamsters with sarcomas†	Latency, weeks‡
pCPGH-19 (1–5 μg)	31/64 (48%)	8–65 (36)
pCPGMH-19 (2.5–5 μg)	2/51 (4%)	10–50
pCPGH-19 (2.5 μg) dig. PvuII	0/9 (<11%)	—
pH-19 (25 μg)	0/10 (<10%)	—

^*Plasmid DNA was linearized by SspI digestion at the unique site in the plasmid vector. Digestion by PvuII which cleaves three times within the v-src coding sequence was used as a control. 

^† Frequency of hamsters with sarcomas at the site of inoculation is expressed as the number of hamsters developing sarcomas/number of hamsters inoculated. 

^‡ The mean latencies (in weeks) are given in parentheses. Inoculated hamsters were followed for 80 weeks. The ten hamsters inoculated with the high dose of pH-19 plasmid DNA were followed for two years.