CD44 and sarcoma: We also examined Matrigel, a biological compound derived from the extracellular matrix of Engelbreth-Holm-Swarm mouse sarcoma cells, which consists of proteins (such as laminin, collagen, and entactin), proteoglycans (like heparan sulfate proteoglycans), and various growth factors (including EGF, TGF-β, bFGF, and IGF-1).