IKZF1 and acute lymphoblastic leukemia: The complete coding sequence of IK6 was amplified by polymerase chain reaction (PCR) from an ALL cell line Sup-B15 (sFig. 2a) and cloned into lentiviral expression vector pHR-SIN-CSIGW to investigate the biological effect of leukaemic alterations of IKZF1 and the underlying programs in HSCs (sFig. 2b).