CSPG4 and breast cancer: This suggests that a decrease in CS-A after CSPG4 siRNA treatment (Figure 4E) is due to reduced expression of CSPG4 and not of CHST11. These data suggest that CSPG4 participates in forming P-selectin ligands on the surface of highly aggressive human breast cancer cells, but obviously it is not the only PG involved in CS-GAG presentation.