Antineoplastic Combined Chemotherapy Protocols/pharmacology; Enzyme Inhibitors/pharmacology; Galactolipids/pharmacology; Neoplasm Proteins/antagonists & inhibitors; Nucleic Acid Synthesis Inhibitors; Spinacia oleracea/chemistry; Animals; Antimetabolites, Antineoplastic/chemistry; Antimetabolites, Antineoplastic/pharmacology; Apoptosis/drug effects; Carcinoma/drug therapy; Carcinoma/metabolism; Carcinoma/pathology; Cattle; Cell Cycle/drug effects; Cell Line, Tumor; Cell Proliferation/drug effects; DNA-Directed DNA Polymerase/metabolism; Deoxycytidine/analogs & derivatives; Deoxycytidine/chemistry; Deoxycytidine/pharmacology; Drug Synergism; Enzyme Inhibitors/isolation & purification; Galactolipids/isolation & purification; Humans; Isoenzymes/antagonists & inhibitors; Isoenzymes/metabolism; Kinetics; Neoplasm Proteins/metabolism; Pancreatic Neoplasms/drug therapy; Pancreatic Neoplasms/metabolism; Pancreatic Neoplasms/pathology; Plant Extracts/chemistry; Rats; Gemcitabine