Smoothelin is a novel cytoskeletal
protein that reacts with the 59 kDa and 100 kDa protein, corresponding to
Smoothelin A and B, respectively, which are exclusively found in smooth muscle
cells (SMC). Cells with SMC-like characteristics, such as myofibroblasts and
myoepithelial cells, as well as skeletal and cardiac muscle do not contain
Smoothelin. Smoothelin is exclusively expressed in fully differentiated
(contractile) smooth muscle cells such as human detrusor and in the human
muscularis propria. Studies have also shown Smoothelin as a potential tool in
the pathologic staging of invasive urothelial carcinoma, overactive bladder, and
in the evaluation of atherosclerotic lesions.