UASt regulates expression of a mutant form of the "NUP98-HOXA9" (NA9) translocation, in which a point mutation (W506A) has been introduced to obliterate PBX interaction. (NA9 fuses the amino-terminal part of human NUP98 to the carboxyl-terminal part (DNA binding domain) of human HOXA9, and causes Acute myeloid leukemia (AML).