Cytokine-like protein 1 is a secreted protein. It is expressed in CD34+ cell populations of bone marrow and cord blood which function as hematopoietic stem/progenitor cells. It is not expressed in CD34– cells. Experiments with knock-out mice (Cytl1-/-) suggest that CYTL1 is required for the maintenance of cartilage homeostasis rather than cartilage and bone development, and loss of CYTL1 function is associated with experimental osteoarthritic cartilage destruction in mice.