Calponin (34 Kd polypeptide) is a
cytoskeleton-associated actin-binding protein that also interacts tropomyosin
and calmodulin. Calponin has been found to be useful as a marker for
myoepithelial and basal lamina in differentiating microinvasive from in
situductal carcinomas of the breast. Calponin has also been useful in malignant
myoepithelium and pleomorphoric adenoma of salivary gland as well as a useful
marker for fine needle aspirates of papillary breast
lesions.