PDGFRB and breast carcinoma: Although some previous studies have shown that Combogin induced caspases-independent apoptosis in breast cancer cells [24,33], and is preferentially cytotoxic to cells expressing PDGFR [25], it exerts non-cytotoxicity to B-lymphoma cells, including KSHV-infected PEL cells, at a low concentration of less than 1 μM.