Tumour regression in mice inoculated with different vaccines. Mice were inoculated with 0.5 × 106 C3 tumour cells to induce tumours and subsequently injected with vaccine (5 μg protein or 100 μg DNA in 100 μl) in two sites per animal when the tumours were clearly palpable. Surface tumour size was measured over time. Because some tumours became bloody in some animals of the control group (empty vectors), the experiment was terminated at day 14. Data gives the mean ± SEM of the indicated group (n = 10). A) Animal groups injected with 100 μg pTH DNA, or 100 μg pTH-16E7SH DNA, or 50 μg plant-produced ZERA-16E7SH protein or ZERA-16E7SH protein plus adjuvant (IFA). B) Animal groups injected with control DNA (pTH) or plant-produced ZERA-eGFP protein.