A prominently studied disease is acute promyelocytic leukemia (APL), which is caused by the fusion genes PML-RARα and PLZF-RARα, which results in the atypical selection of corepressors suppressing the RA-targeted genes responsible for the terminal differentiation of promyelocytes (Altucci and Gronemeyer, 2001). This evidence concerns the gene PML and acute promyelocytic leukemia.