Monoclonal Antibody 703D4

**Semantic type:** Amino Acid, Peptide, or Protein|Immunologic Factor|Pharmacologic Substance

**Definition:** A monoclonal antibody which recognizes the heterogeneous nuclear ribonucleoprotein (hnRNP) A2/B1, a potential epithelial marker in the detection of early lung cancer, on cell surfaces. This protein is responsible for posttranscriptional regulation of gene expression by capping, splicing, polyadenylation, and cytoplasmic transport of mRNAs. Its detection in bronchial lavage specimens was shown to predict predicts the presence of a neoplasm with 96% sensitivity and 82% specificity earlier than routine chest X rays or sputum cytology. (NCI)