Table 1. Long-term protection of vaccinated animals.

Vaccination	Mean number of pulmonary tumour nodules
Tc-ErbB2/Th-HA	0 (n=5)
Tc-ErbB2	0 (n=2)
None	>250 (n=5)

After rejection of initial tumour challenge, tumour-free mice from the experiment shown in Figure 2 were re-challenged by i.v. injection of Renca-lacZ/ErbB2 cells after day 96. After 28 days, before mice developed any apparent disease symptoms, they were killed, lungs were excised, and pulmonary tumour nodules were visualised by X-gal staining of excised organs and counted. Naïve animals injected with Renca-lacZ/ErbB2 cells served as a control. One of the three mice in the Tc-ErbB2 vaccinated group that had rejected the initial tumour challenge died for unknown reasons before i.v. re-challenge could be performed.