PDGFRA and intrahepatic cholangiocarcinoma: Recent investigations have brought to light the interaction between ICC in the smooth muscle layer of the gastrointestinal tract and PDGFRα-positive cells (cells expressing platelet-derived growth factor receptor alpha) with SMC through gap junctions (55–57), resulting in the formation of SIP (Smooth Muscle-Interstitial Cells of Cajal) corpuscles (58).