JAK2 and T-cell leukemia: In contrast, when EμSRα-TEL-JAK2 mice were bred on a Tcra−/−;Relb−/− background, we found that these mice developed T-cell leukemia with statistically significant delayed onset as compared to TEL-JAK2;Tcra−/−;Relb+/+ littermates (median survival of 18.5 and 13 weeks, respectively; P<0.01) (Figure 4A).