the present invention relates to long term multiplication and permanent establishment of a cell line of human liver epithelial cells . the human liver epithelial cell line is capable of mitotically proliferating and continuously growing in vitro under suitable environmental conditions in suitable culture media . a method of producing an immortalized human liver epithelial cell line is also disclosed . the invention also relates to serum - free cell medium developed to support long term multiplication and permanent establishment of a cell line of human liver epithelial cells . the medium may contain an effective cell growth promoting amount of calcium ions ; an effective cell growth promoting amount of glucose ; an effective amount of insulin to aid cells in glucose uptake ; an effective cell growth promoting amount of hydrocortisone ; an effective amount of epidermal growth factor to bind epidermal growth factor receptors on cells ; an effective amount of transferrin to increase dna synthesis in cells ; an effective amount of cholera toxin to increase dna synthesis in cells ; an effective amount of triiodothyronine to increase dna synthesis in cells ; and an effective growth promoting amount of mammalian hormones and mitogenic factors , including lipoprotein , cholesterol , phospholipids and fatty acids .