Finally, we performed developmental analysis again using Slingshot and hypothesized 1 cell lineage developmental trajectory, i.e. Lineage: C0 IGLC3+ Myeloma cells→C1 IGHA1+ Myeloma cells→C2 IGHG1+ Myeloma cells→C3 IGHG4+ Myeloma cells (arrows indicate the direction of cell developmental trajectories) (Figures 4O, P). The gene discussed is IGHG4; the disease is plasma cell myeloma.