To assess NK cell functionality and cytotoxicity, GFP-IL-15-NK92 and CAR-IL-15-NK92 cells were co-cultured with CD138-positive multiple myeloma cell lines (MM1.R and MM1.S) and CD138-negative cell lines (Ramos and MDA-MB-231) (Supplementary Figure S2A). Here, SDC1 is linked to plasma cell myeloma.