PREX1 and Bloom syndrome: Similarly, the BLM-induced expression of profibrotic/proinflammatory cytokines was suppressed in Prex1−/− mice compared to WT mice; (2) TGF-β1-induced cellular migration was much slower in Prex1−/− fibroblasts than in WT fibroblasts, which was replicated by the treatment of WT fibroblasts with Rac1 Inh.