Fig 2: Overexpressed Mettl3 affect the protein expression in intratumoral CD8+T cells. The intratumoral CD8+T cells of mouse were treated with CD3/CD28, Lentivirus‐mediated overexpressed Mettl3 for 72 h, and then the levels of ActRIIA, Smad2 and p‐Smad2 proteins were examined by Western blotting. *p < 0.05, **p < 0.01, ***p < 0.001 comparing to control.

Fig 3: Activin A’s influence on functional molecules expression in CD8+ T cells. The tumor tissues lysed for flow cytometry assessment of CD69, CD11c, Ki67, CD49b, and ActRIIA in CD8+T cells. Data shown as mean ± standard. *p < 0.05, **p < 0.01, ***p < 0.001, compared with control group; # p < 0.05,## p < 0.01, ### p < 0.001 compared with activin A group.

Fig 4: Assessment of cytokine expression in ActRIIA high CD8+ T cells. (A) TNF‐α, IFN‐γ, IL‐10, and IL‐9 expression in both subsets were measured via intracellular cytokine staining. (B) ActRIIA high CD8+ T cells and ActRIIA low CD8+ T cells sorted by flow cytometry were treated with CD3/CD28 for 24 h. And the content of TNF‐α, IFN‐γ, IL‐10, and IL‐9 in the culture supernatant was detected by ELISA. Data shown as mean ± standard. *p < 0.05, **p < 0.01, ***p < 0.001 compared with ActRIIA low CD8+ T cells.

Fig 5: The expression of signaling molecules in the activin signaling pathway in CD8+ T cells. (A) Quality of isolated T cells was confirmed via anti‐CD3 and anti‐CD8 antibody staining. (B) Quantitative RT‐PCR identified ActRIIA, ActRIIB, Smad2, 3,4 in mouse CD8+ T cells. (C) Verified ActRIIA expression on CD8+ T cells by flow cytometry. (D) The expression of ActRIIA in CD8+ T cells from peripheral blood, spleen, and lymph nodes of mice was detected by RT‐PCR. Data shown as mean ± standard. *p < 0.05, **p < 0.01, compared with blood.