Small gastrointestinal stromal tumor in the stomach: identification of precursor for clinical gastrointestinal stromal tumor using c-kit and α-smooth muscle actin expression.
Most GISTs (95%) express Kit (CD117), CD34 (70%), and heavy caldesmon (80%), whereas 25% are positive for smooth muscle actin and less than 5% for desmin.
Because the tumor expressed CD34 and c-kit gene product, but did not express smooth muscle actin or S-100 protein, it was diagnosed as an uncommitted type of GIST.