GZMB and plasma cell myeloma: When co-cocultured with RPMI-8226 myeloma cells with YBX1 knockdown, the frequencies of IFN-γ+ and GZMB+ cells among CD8+ T cells were significantly higher than those in CD8+ T cells co-cultured with control RPMI-8226 cells (Additional file 1: Fig. S15B, C).