The Lin28-Let-7 stem cell differentiation regulatory pathway is responsible for maintaining stem cell pluripotency. Specifically, Lin28 causes uridiylation of the let-7 miRNA precursor, which prevents differentiation processing by Dicer. Instead, the Uridylated let-7 is degraded by a previously unidentified exonuclease protein. In the article “A role for the Perlman syndrome exonuclease Dis3l2 in the Lin28-let-7 pathway” HM Chang, et al.