Here we observed that IKZF1 binds to the promoter region of CRLF2 and directly suppresses the promoter activity of CRLF2. Our data provide evidence that IKZF1 suppresses CRLF2 expression and conversely, that IKZF1 knockdown increases CRLF2 expression in ALL cells. Here, IKZF1 is linked to acute lymphoblastic leukemia.