Topical all‐trans retinoic acid (atRA) treatment enhances effector CD8+ T‐cell response at tumour sites. (a, b) Representative flow cytometry data and averaged percentages of Granzyme B+, TNF‐α
+ and IFN‐γ
+ (a) as well as Ki67+ (b) cells in CD8+ T cells. (c) Representative flow cytometry data and averaged percentages of IFN‐γ
+ and Ki67+ cells in CD4+ T cells. Columns and error bars represent mean ± SEM (n = 5 to n = 7 per group). *P < 0·05, **P < 0·01, ***p < 0·001, NS = no significance. Similar results were obtained from three independent experiments.