It has been reported that the PDGFRα-positive cells (formerly called FLC) express nitric oxide-sensitive soluble guanylate cyclase in the guinea pig GI tract, SK3 and purinergic receptors in the murine intestine and in the muscle coat of human stomach and colon, and that they are closely related to ICC, nNOS- and SP-positive nerve fibres [21–24, 33, 34]. The gene discussed is NOS1; the disease is intrahepatic cholangiocarcinoma.