So function number one is it acts as joint lubricants. Function number two, it basically functions in the structural components of tissues and that includes connective tissue, for instance, bone and cartilage. Number three it functions to bind cells to extracellular matrix. And number four it actually functions to move molecules through the extracellular matrix. Now one example of a well studied proteoglycan that we know a lot about is aggregate. And aggregate is found in the extracellular matrix of connective tissues such as Cartilage.