To exclude the contributions of other cells in Prrx1-mediaeted cardiac fibrosis, we generated fibroblast-specific Prrx1 gene knockout (Prrx1FB−/-) mice by crossing Prrx1flox/flox mice with Col1a2-iCreER mice followed by MI surgery for 4 weeks (Online Fig. 7A and B and Online Fig. 8A). Here, PRRX1 is linked to fibrosis.