Moreover, co-expression of CD33∆E2 did not impact GO-induced cytotoxicity in AML cells endogenously displaying CD33 on the cell surface, as evidenced by our findings in ML-1 and OCI-AML3 cells, indicating that CD33∆E2 does not interfere with the ability of CD33FL to serve as carrier for intracellular delivery of cytotoxic drugs to CD33-expressing leukemia cells. The gene discussed is CD33; the disease is acute myeloid leukemia.