As a result, notable CD33+ target cell killing was detected via standard chromium release cytotoxicity assays already after 24 h (Fig. 7c), leading to approximately 50% to 70% of tumor cell lysis after 48 h of incubation in the presence of bsAb-releasing or bsAb-releasing/4-1BBL-expressing MSCs respectively (Fig. 7d). This evidence concerns the gene CD33 and neoplasm.