Our unsorted scRNA-seq strategy enabled cell–cell communication analysis between the tumor and TME in the BM of MM patients, revealing that the tumor cell populations might be the major source of cancer-related signals involving NCAM, MPZ, GAS6, ALCAM, BAG, and CCL. GAS6, which encodes the GAS ligand, is overexpressed in many cancers and promotes cancer cell proliferation and survival44. This evidence concerns the gene NCAM1 and neoplasm.