Protection from tumor challenge in the mammary fat pad after vaccination with SINCP or Adeno. Groups of mice were vaccinated once with SINCP-neu (a plasmid containing Sindbis virus genes and the gene for rat HER2/neu) or SINCP-βgal. (a) or with Adeno-neu (an E1,E2a-deleted adenovirus also containing the gene for rat HER2/neu) or Adeno-empty (adenovirus lacking an inserted gene) (b). Two weeks after vaccination with SINCP and 6 weeks after vaccination with Adeno, the mice were challenged with A2L2 cells injected into a mammary fat pad. Thirty-five days after the tumor challenge, the mice were killed and if a solid tumor was present, the mass of the tumor was determined. Each symbol represents one mouse. Horizontal bars indicate means.