The expression of the dominant-negative Ikaros isoform IK6 in the T-ALL (Jurkat) and B-ALL cell lines (RS4;11, Nalm6) lifted the transcription suppression of FUT4, which fucosylates α5β1 on leukemia cells and tightens the adhesion of ALL cells to fibronectin in the ECM. Here, FUT4 is linked to acute lymphoblastic leukemia.