Deletion of Smad4 in fibroblasts leads to defective chondrocyte maturation and cartilage production in a TGFβ type II receptor independent manner

► FSP1+ fibroblasts participate in elastic cartilage and fibrocartilage production. ► Loss of Smad4 in fibroblasts results in a short ear phenotype. ► Chondrocyte maturation is conducted via Smad4 signaling. ► BMP-5 induces differentiation of ear chondrocytes.