The mechanisms of cell turnover including cell proliferation and cell differentiation were complex. Planarians possess amazing regeneration ability and undergo cell turnover throughout life. We identified a homologous gene of ERas by RNAi in Dugesia japonica. Knocking-down DjERas resulted in regeneration and homeostasis defects. Furthermore, we found that the expression of neoblasts and late progeny marker gene decreased in DjERas RNAi planarians. Our studies indicated that down-regulation of DjERas inhibited the proliferation and differentiation of stem cells through the conserved signaling pathway, resulted in the inability of the planarian to regenerate and maintain homeostasis. Our results suggest that DjERas plays a crucial role in the process of cell turnover. (C) 2019 Elsevier Inc. All rights reserved.