UCMA and arthritic joint disease: Consistent with our loss-of-function data in Fig. 4A–E, mice treated with recombinant Ucma developed alleviated arthritis-triggered cartilage degeneration during SIA, determined as cartilage erosion (Fig. 4F, H) and proteoglycan loss (Fig. 4F, I) on safranin-O stained paw sections.