We also observed an increase of activated CD4+ T cells (CD38+CD4+ T cells) with higher cytotoxic function (CD107a+ CD4+ T cells) in the spleens of previously cured mice that were rechallenged with the poorly immunogenic pMMR neuroblastoma tumor cells (Figures 7J, 7K, and S5H). Here, CD4 is linked to neuroblastoma.