Several studies have addressed whether beta-cells lost during the development of diabetes may be replenished by potential islet cell progenitors such as duct cells [34], acinar cells [15], trans-differentiation of non-beta islet endocrine cells [10], by replication and regeneration of existing beta-cells [12], [13], [35] or as recently proposed dedifferentiation into progenitor-like cells expressing early transcription factors such as Ngn3 and Oct4 [8]. The gene discussed is POU5F1; the disease is diabetes mellitus.