RUNX1 strongly induces expression of p16CDKN2A and our previous studies showed that RUNX1 SLGA fails in Leiden human fibroblasts that lack expression of p16CDKN2A due to a homozygous mutation that does not affect the p14ARF reading frame.24, 32 Notably, p16CDKN2A expression can also be lost in t(12;21) leukemias due to gene deletion33 or promoter hypermethylation in ALL34 and gene deletion has been detected in the prototypic REH cell line.35 It was therefore interesting to test the resistance of REH cells to ectopic RUNX1. Here, RUNX1 is linked to leukemia.