KRT19 and squamous cell carcinoma: The serum levels of carcino-embryonic antigen (CEA), carbohydrate antigen 199 (CA199), carbohydrate antigen 125 (CA125), neuron-specific enolase (NSE), cytokeratin 19 fragment (CYFRA21-1) and squamous cell carcinoma (SCC) in 40 lung cancer cases undergoing video-assisted thoracoscopic lobectomy were measured before operation and 24 h after operation.