1) The document studies changes in replication timing of the Pleiotrophin (Ptn) gene during the differentiation of mouse embryonic stem cells (mESCs) to neural precursor cells (NPCs). 2) It finds that Ptn switches from late to early replication during differentiation, coinciding with increased transcriptional activity of Ptn. 3) To study if transcriptional induction is necessary for replication timing changes, the authors engineered targeted deletions of the Ptn promoter and upstream nucleosome-free region, finding the deletion altered Ptn's replication timing.