CSPG4 and breast carcinoma: Anti-CSPG4-SB-Saporin, specific for the melanoma associated antigen chondroitin sulfate proteoglycan 4 (CSPG4), caused a concentration-dependent decrease in cell viability of CSPG4-high A375 and A2058 melanoma cell lines, but had no toxic effects on the CSPG4-low SBCL-2 and SKBR-3 breast cancer cells (Fig. 1d).