The highly glycosylated TR domain of MUC4 is believed to impede tumor cell interaction with extracellular matrix (ECM) proteins by obstructing integrin accessibility to ECM ligands in a steric manner.[40] Consequently, both MUC4/X[14] and MUC4/Y,[15] which lack exon 2, have been implicated in promoting tumorigenesis and metastasis and are recognized to exhibit oncogenic activity. The gene discussed is MUC4; the disease is neoplasm.