CD4 and neoplasm: Compared to age-matched naive, or mice inoculated with tumour cells for the first time, CD4+ and CD8+ T-cell proliferation was significantly higher in animals experiencing re-challenge, and changes in CD8+ effector memory cell phenotype were consistent with a T-cell memory response to antigen re-exposure (Supplementary Fig. 5c,e; Student's t-test P<0.05).