This suggest that these mutations might confer clonal fitness.74 Tamai et al developed a transgenic mouse carrying KMT2A-AFF1 and KRASG12V that developed B-cell lymphoma/ALL in 6 months.72 Previous mouse models failed to recapitulate the human leukemia induced by KMT2A-AFF1. Here, AFF1 is linked to acute lymphoblastic leukemia.