YTHDF2 depletion in DC boosts RT antitumor immunity by enhancing antigen cross-presentation. (A) B16F10-OZ tumor growth curves in WT and Ythdf2-cKO mice with or without IR (n = 5, mean ± SD). (B) Survival rate of B16F10-OZ–inoculating mice with or without IR. (C) Scheme of KPC344 orthotopic pancreatic cancer models and treatment of CT imaging–guided RT. (D–I) Flow cytometry on immune profiles of (D) CD4⁺ T cells, (E) CD8⁺ T cells, (F) macrophages, (G) cDCs, (H) cDC1s, and (I) cDC2s residential in B16F10-OZ tumors on day 5 after IR (n = 5, mean ± SEM). (J) CFSE⁺ DC frequency in tumor-infiltrating DCs (n = 4, mean ± SEM). (K and L) MFI of (K) CD80 and (L) CD86 in BMDCs (n = 3, mean ± SEM). (M) Viability of DCs before and after coculturing with CD8⁺ T cells (n = 3, mean ± SEM). (N) ELISPOT assay on IFN-γ secreted by CD8⁺ T cells stimulated with YTHDF2 inhibitor–treated DCs in coculture with irradiated or nonirradiated tumor cells (n = 4, mean ± SEM). (O) ELISPOT assay on IFN-γ secreted by CD8⁺ T cells stimulated with WT or cKO DCs in coculture with irradiated or nonirradiated tumor cells (n = 4, mean ± SEM). (P) MFI of H2Kb-SIINFEKL in migratory DCs from WT or cKO mice inoculated with B16-OVA tumors (n = 3, mean ± SEM). (Q) ELISPOT assay on IFN-γ secreted by CD8⁺ T cells stimulated with migratory DCs in WT or cKO mice inoculated with B16-OVA tumor cells (n = 3, mean ± SEM). (R) ELISPOT assay on IFN-γ secreted by CD8⁺ T cells stimulated with WT or cKO DCs cocultured with different concentrations of SIINFEKL (n = 3, mean ± SEM). (S) MFI of H2Kd in BMDCs cocultured with irradiated 4T1-HA cells (n = 3, mean ± SEM). (T) MFI of H2Kd-HA tetramer–positive CD8⁺ T cells, which were stimulated with DCs cocultured with irradiated 4T1-HA cells (n = 3, mean ± SEM). (U) B16F10-OZ tumor growth curves on mice with CD8⁺ T cell depletion by αCD8 (200 μg/mouse, twice weekly), starting 1 day before IR (n = 5, mean ± SD). (V) H&E staining of lungs collected from LLC tumor–bearing mice 30 days after tumor inoculation; scale bars: 2 mm. Statistical analysis was performed using two-sided unpaired Student’s t test (A and D–U); ns, P > 0.05; *P < 0.05; **P < 0.01; ***P < 0.001.