PTPN2 and acute lymphoblastic leukemia: To validate these findings, we performed fluorescence-based competition assays comparing the relative growth of mixtures of isogenic Ptpn2 KO or control B-ALL cells treated with CAR-T therapy in vivo or in vitro and found that Ptpn2 KO cells depleted in mice treated with anti-mCD19 CAR-T therapy as well as in vitro (Fig. 3e).