The CEB25-L111(T) array is stable in WT cells, it becomes unstable upon addition of Phen-DC3 Trifluoromethanesulfonate or deletion of PIF1. A CEB1-WT array is rather stable but undergoes frequent rearrangements upon addition of 10 μM Phen-DC3 Trifluoromethanesulfonate (Phen-DC3) in WT cells. It is found that the c-Myc allele displays significant destabilization upon Phen-DC3 Trifluoromethanesulfonate treatment and PIF1 deletion. It is also highly destabilized in the presence of Phen-DC3 Trifluoromethanesulfonate or in the absence of PIF1. The CEB1-loop CEB25 allele remaines fully stable in both PIF1-treated and WT cells[2].