Mutations in FOXO1 affecting phosphorylation sites and the DNA binding domain. (A) Mutations affecting FOXO1 in relation to the exons, protein domains, and phosphoinositide 3-kinase/AKT phosphorylation sites. Sequencing of FOXO1 revealed mainly missense mutations (green circles) with two deletions (orange triangles) located primarily in the first exon of FOXO1. A majority of the recurrent hot-spot mutations affect the consensus [RxRxxT] PKB/AKT recognition motif surrounding the T24 phosphorylation site. A cluster of mutations were also found in the Forkhead DNA binding domain. •Sites in which the mutation has been confirmed to be somatic in ≥1 patient sample. (B) Cross-species sequence conservation of the N-terminal RxRxxT site in FOXO1 proteins. *Sites of recurrent mutations in DLBCL samples. (C) Ribbon representation of the FOXO1 DBD-DNA complex (green). The sites of DBD mutations are marked with the wild-type amino acid structures (blue) and mutated amino acid structures (red). Many of the FOXO1 mutations in the Forkhead domain are found within the helical structures.