Monoclonal Anti-Cellular Fibronectin (mouse IgM isotype) is derived from the hybridoma produced the fusion of mouse myeloma cells and splenocytes from immunized mice. Fibronectin is an extracellular matrix protein composed of two nearly identical disulfide-bound polypeptides with typical molecular weights of 220-240 kDa. Cellular fibronectin is structurally and antigenically similar to cold insoluble globulin from plasma and polyclonal antibodies to either form usually cross-react. The protein contains several functionally and structurally distinct domains, which may bind to cell surfaces, collagen, heparin, etc.