HSPG2 and breast cancer: However, analyzing our mass spectrometry data11, we found an abundance of both heparan sulfate (HS) and chondroitin sulfate (CS) proteoglycans, including CD44 (HS/CS-proteoglycan), HSPG2 (HS-proteoglycan), glypican-1 (GPC-1; HS-proteoglycan), versican (VCAN; CS-proteoglycan) and syndecan-1 (SDC1; HS/CS-proteoglycan), in BC exosomes (Supplementary Fig. 7C11).