APC and neoplasm: The tumor numbers (Lgr5/Apc: 77.8 ± 9.9 Lgr5/Arf1/Apc: 28.2 ± 7.8; CD4/Lgr5/Arf1/Apc: 42.2 ± 6.1; CD8/Lgr5/Arf1/Apc: 55.8 ± 15.2; CD4+CD8/Lgr5/Arf1/Apc: 71.2 ± 14.1; MYC-ON/DMSO: 89.6 ± 24.8; MYC-ON/GCA: 26.3 ± 18.6; MYC-ON/GCA/CD4: 51.0 ± 25.0; MYC-ON/GCA/CD8: 67.3 ± 22.6; MYC-ON/GCA/CD8 + CD4: 87.5 ± 33.5) were dramatically increased (Fig. 4a, c–e), while the lifespans were significantly shortened in Arf1-ablated Lgr5/Apc and MYC-ON mice after the depletion of CD8+ and CD4+ T cells (Fig. 4b, f).