DPP4 and ataxia telangiectasia: By contrast, the proportion of GFP+DPP4+ cells reduced while that of GFP+DPP4− cells increased at 4 weeks old as AT fibrosis progressed (Fig. 5c), and the proliferation capacity of GFP+DPP4+ was greater than that of GFP+DPP4− cells (Supplementary Fig. 9h, i).