RARA and acute promyelocytic leukemia: We then showed that FOXC1 downregulation in APL is due to binding of PML/RARA to a specific motif localized in the FOXC1 promoter region (from –398 to –391), and that ATRA addition decreases PML-RARA binding and unlocks FOXC1 in both NB4 and PR9 cell lines.