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). Here, RARA is linked to acute promyelocytic leukemia.