PRF1 and plasma cell myeloma: The hybrid cell lines (HU266 and HRC) stimulated significant elevation of IFNγ and perforin releasing cells in response to restimulation with MUC1, CS1, hTERT, and MAGE C1 derived peptide-pulsed T2 cell line, compared with cultured PBMCs without further re-stimulation, the parent myeloma cell line U266, and their parent APC cell line, HMY2 (except for MAGE C1 specific IFNγ releasing response).