FOXO1 and precursor B-cell acute lymphoblastic leukemia: Strikingly and in contrast with FOXO3, which displayed tumour suppressor activity (p = 0.0069), FOXO1 was ranked second (p = 2.41 × 10−8) in the list of essential genes, a finding consistent with previous observations that inhibition or knock-down of FOXO1 negatively affects B-ALL growth [42, 43].