The RAR receptor is dependent on retinoic acid for regulation of transcription.Eight other rare gene rearrangements have been described in APL fusing RARA to promyelocytic leukemia zinc finger (PLZF), nucleophosmin, nuclear matrix associated, signal transducer and activator of transcription 5b (STAT5B), protein kinase A regulatory subunit 1α (PRKAR1A), factor interacting with PAPOLA and CPSF1 (FIP1L1), BCL-6 corepressor or oligonucleotide/oligosaccharide-binding fold containing 2A (NABP1) genes. Some of these rearrangements are ATRA-sensitive or have unknown sensitivity to ATRA because they are so rare; STAT5B/RARA and PLZF/RARA are known to be resistant to ATRA.The fusion of PML and RARA results in expression of a hybrid protein with altered functions. This fusion protein binds with enhanced affinity to sites on the cells DNA, blocking transcription and differentiation of granulocytes. It does so by enhancing interaction of nuclear co-repressor (NCOR) molecule and histone deacetylase (HDAC). Although the chromosomal translocation involving RARA is believed to be the initiating event, additional mutations are required for the development of leukemia.RARA/PLZF gene fusion produces a subtype of APL that is unresponsive to tretinoin therapy and less responsive to standard anthracycline chemotherapy hence leading to poorer long-term outcomes in this subset of patients. Diagnosis
Acute promyelocytic leukemia can be distinguished from other types of AML based on microscopic examination of the blood film or a bone marrow aspirate or biopsy as well as finding the characteristic rearrangement. The presence of promyelocytes containing multiple Auer rods (termed faggot cells) on the peripheral blood smear is highly suggestive of acute promyelocytic leukemia.
Obstruction  may refer to:

Places
Obstruction Island, in Washington state
Obstruction Islands, east of New Guinea

Medicine
Obstructive jaundice
Obstructive sleep apnea
Airway obstruction, a respiratory problem
Recurrent airway obstruction
Bowel obstruction, a blockage of the intestines. Gastric outlet obstruction
Distal intestinal obstruction syndrome
Congenital lacrimal duct obstruction
Bladder outlet obstruction

Politics and law
Obstruction of justice, the crime of interfering with law enforcement
Obstructionism, the practice of deliberately delaying or preventing a process or change, especially in politics
Emergency Workers (Obstruction) Act 2006

Science and mathematics
Obstruction set in forbidden graph characterizations, in the study of graph minors in graph theory
Obstruction theory, in mathematics
Propagation path obstruction
Single Vegetative Obstruction Model

Sports
Obstruction (baseball), when a fielder illegally hinders a baserunner
Obstructing the field

See also
The Five Obstructions, a 2003 film
USS Obstructor, an American minelayer ship used in World War II