HOXA1 and acute promyelocytic leukemia: In the NB-4 human acute promyelocytic leukemia (APL) cell line, it is strongly upregulated during all-trans retinoic acid (ATRA)-driven granulocytic differentiation, where it selectively modulates the induction of HOXA1/HOXA4 and of the myeloid maturation markers CD11b, CD18, and CD11c, meanwhile repressing CD49d (46, 47).