FOXO1 and acute lymphoblastic leukemia: Interestingly, we noticed that the FOXO1 expression was deficient in this patient with MEIS1–FOXO1 fusion, suggesting an underlying mechanism in vivo mediating the low expression of the wild-type allele of FOXO1. Notably, we also found that there was a correlation between low FOXO1 transcription and ALL relapse among the enrolled patients and subjects in public datasets, and FOXO1 transcription was almost silenced in those relapsed patients as compared with their diagnostic counterparts, suggesting that FOXO1 status can be a valuable prognostic feature in ALL.