To assure that mouse mAb 16A11 was specific for HuD-antigen in both human and mouse HuD-positive cancer cells, we first tested the reactivity of the antibody to cell extracts obtained from SCLC, neuroblastoma, and extracts those extracted from leukemia and mouse T lymphoma control cell lines by Western blot. This evidence concerns the gene ELAVL4 and leukemia.