Haptocorrin (also known as HC, R protein, and transcobalamin I, TCN1) is another glycoprotein secreted by the salivary glands which binds to vitamin B12. Vitamin B12 is acid-sensitive and in binding to transcobalamin I it can safely pass through the acidic stomach to the duodenum. In the less acidic environment of the small intestine, pancreatic enzymes digest the glycoprotein carrier and vitamin B12 can then bind to intrinsic factor. This new complex is then absorbed by the epithelial cells (enterocytes) of the ileum. Inside the cells, vitamin B12 dissociates once again and binds to another protein, transcobalamin II (TCN2); the new complex can then exit the epithelial cells to be carried to the liver.