Dulbecco's modified Eagle's medium (5,6 mmol/l) supplemented with 2% bovine serum albumin (BSA) fraction V , 50 μmol/L 2-β-mercaptoethanol, 10 mmol/L nicotinamide, 5.5 μg/ml transferrin, 6.7 ng/ml sodium selenite, 100 units/ml penicillin, and 100 μg/ml streptomycin