Regnase-1 deletion promotes formation of memory-like CAR-T cells with recall capacity. (A-B) CD8⁺ WT and KO CAR-T cells were cotransferred 1:1 into tumor-bearing mice. Organs were harvested at indicated time points. Representative plots are shown for spleen. (A) Frequencies of CD44⁺CD62L⁻ and CD44⁺CD62L⁺ WT and KO CAR-T cells. (B) Frequencies of CD127⁺KLRG1⁻ and CD127⁻KLRG1⁺ WT and KO CAR-T cells. (C-F) CD8⁺ WT and KO CAR-T cells were cotransferred 1:1 into tumor-bearing mice, sorted from spleens 21 days later, and cotransferred 1:1 again into naive recipients that received hCD19⁺ B-ALL cells the following day. Spleens were harvested 5 days later. (C) Experimental design schematic. (D) Absolute number of WT and KO CAR-T cells 5 days after secondary tumor stimulation. (E) Frequencies of CD44⁺CD62L⁻ and CD44⁺CD62L⁺ WT and KO CAR-T cells 21 days after primary tumor stimulation (left) and 5 days after cotransfer and secondary tumor stimulation (right). (F) Frequencies of IFNγ⁺, IL-2⁺, TNFα⁺, and granzyme B⁺ (GzmB) WT and KO CAR-T cells from spleens 5 days after cotransfer and secondary tumor stimulation. Endogenous host CD8⁺ T cells are included as a gating control. Significance was determined by paired Student t test (A-B,D,F) or 2-way analysis of variance (ANOVA) with the Tukey posttest for multiple comparisons (E). Data are shown as mean plus or minus SEM and represent 2 independent experiments with 3 to 5 mice per group (A-B,D-F). *P < .05; **P < .01; ***P < .001; ****P < .0001.