CD4 T cell depletion severely impaired the development of antitumor T-cell memory. Seventy days after HSCT, tumor-free survivors in Figure 4C were rechallenged with 10⁵ wild-type AGN2a tumor cells injected subcutaneously, and followed for survival (ie, ability to reject the tumor cells). Survival curves are shown, and the data represent the combined results of 2 or 3 separate experiments. Each group consisted of 5 to 9 total mice.