Serglycin present on myeloma cell surface promotes the adhesion of myeloma cells to collagen I. The adhesion of myeloma cells to collagen I but also the interaction of soluble collagen I with myeloma cells via cell-surface serglycin enhances the biosynthesis and secretion of MMP2 and MMP9, which are involved in bone destruction (57) (Figure 3). Here, MMP2 is linked to plasma cell myeloma.