Disruption of NBs in APL is caused by expression of the oncogenic fusion protein PML-RARα (PML-retinoic acid receptor alpha) resulting from the t(15; 17) chromosomal translocation (de Thé et al., 1991; Kakizuka et al., 1991; Dyck et al., 1994; Weis et al., 1994). This evidence concerns the gene RARA and acute promyelocytic leukemia.