IKZF1

IKZF1 encodes IKAROS, a zinc finger DNA-binding transcription factor that regulates hematopoiesis, lymphoid lineage development, and mature lymphocyte differentiation^[1][2]. Mechanistically, IKAROS binds upstream regulatory elements, recruits chromatin-remodeling complexes, and activates or represses transcription in genes controlling proliferation, development, and leukemia progression^[3]. In B-cell acute lymphoblastic leukemia (B-ALL), IKZF1 deletions cause loss of normal IKAROS function, confer leukemic stem cell properties, and associate with treatment resistance and inferior outcomes^[2]. In BCR-ABL1-positive ALL, recurrent IKZF1 deletions occur frequently and generate dominant-negative isoforms with cytoplasmic localization and oncogenic activity^[4]. Compared with DNA-binding IKAROS isoforms, shorter isoforms lacking N-terminal zinc fingers cannot bind transcriptional targets normally but retain dimerization domains and inhibit longer IKAROS partners^[1]. The Ik6 isoform is especially relevant because Philadelphia chromosome-positive ALL cells express high levels of non-DNA-binding Ik6 after IKZF1 genomic deletions, and these isoforms localize in the cytoplasm rather than the nucleus^[5]. For experimental applications, CK2-mediated phosphorylation impairs IKAROS DNA binding, gene regulation, and tumor-suppressor function, while CK2 inhibitors restore IKAROS activity in preclinical ALL models^[6].