CSGALNACT1 and osteoarthritis: CS is one of the major components of articular cartilage, and Csgalnact1-null mice exhibit some osteoarthritis-like changes in cartilage, such as a decreased level of aggrecan and link protein 1, a rapid catabolism of aggrecan, and abnormally aggregated and disarranged type-II collagen fibers [27], [28].