Though serglycin has long been considered as an intracellular PG located primarily in storage granules and secretory vesicles [19, 20], we and others found that myeloma cells constitutively secrete serglycin and that serglycin is the major PG released ( > 70% of the total) and the only CSPG expressed by myeloma cells [18, 21]. Here, SRGN is linked to plasma cell myeloma.