Astrocytes turned into reactive mitotic cells by cell-cycle translation and Ras-p-Raf1-p-ERK1/2 proteins expression. Mfn2 expression both in mRNA and protein levels was decreased in reactive astrocytes. Overexpression of Mfn2 markedly suppressed the proliferation of astrocytes. The mechanism relies on inhibiting Ras-Raf-ERK signaling pathway and blocking cell cycle translation.