RUNX2 and acute myeloid leukemia: Similarly to Lin28A transfection, PMA and ATRA treatment of AML cell lines also induced p21 expression (Figures 3g–i) and a significant cell-cycle arrest in the G2 phase (ME-1: P<0.001 at 48 h, P<0.05 at 72 h; OCI-AML3: P<0.01 at 24 h, P<0.05 at 48 and 72 h; KG-1: P<0.001 at 24 h, P<0.05 at 48 h, P<0.001 at 72 h) (Figure 3k and Supplementary Figure 2f), the G1 phase (MOLM-14: P<0.001 at 72 h) (Figure 3k) or the S phase (NB4: P<0.001 at 24 h, P<0.01 at 48 and 72 h) (Supplementary Figure 2f).