Knockdown of SALL4 inhibits the tumorigenicity of NB4 leukemia cells. Tumor growth in NOD/SCID mice injected with control NB4 cells or SALL4 reduction cells was estimated with caliper measurements. Cells were injected at 2 different dosages, and tumor size was determined on day 21 or 30 after injection. Error bars represent the standard deviation. *P < .05; **P < .01.