PRRX1 and osteoarthritis: Histological analyses revealed that Prrx1-CreERT; Ptch1f/f mice exhibited signs of osteoarthritis with high OARSI scores at 2.5 months of age (2 months after TAM injection) (Figure 2A and B), and increased fibrotic cells lining the damaged cartilage surfaces, which were positive for fibrosis marker FSP1 (Figure 2C and D).