HMGB1 and plasma cell myeloma: There is a possibility that LEN remaining in supernatant of drug-treated myeloma cells enhanced expression of CD86 and phagocytosis of DC at some content; however, lenalidomide did not induce enough DC activation because the amount of HMGB1 secreted from myeloma cells after lenalidomide treatment was less than those by PIs in MUM24 (Figure 2A).