DPP4 and systemic sclerosis: The Rinkevich et al. cell lineage tracing study strongly supports the pseudotime analysis of our data, showing that the SFRP2/DPP4 fibroblast subpopulation in healthy skin is the progenitor of fibrogenic fibroblasts in SSc skin, including both SFRP2hiPRSS23+WIF1− fibroblasts and myofibroblasts26.