RUNX1 and leukemia: We investigated the temporal order of allelic replication of two cancer-related genes (TP53 and AML1) and a non-coding repetitive DNA sequence (CEN17): TP53 is a tumor-suppressor gene, the most commonly mutated gene in human neoplasms (reviewed in [22]); AML1 is an ETS family gene, involved in the 8;21 -- leukemia-abundant translocations (reviewed in [23]); and CEN17 is an array associated with the centromere of chromosome 17, which, as such, is engaged in chromosome segregation [18].