Which factors are required for proper cell growth of HeLa cells?

Which factors are required for proper cell growth of HeLa cells? A. Fetal Bovine Serum B. proper temperature of 37 degrees OC. proper gas environment and CO2 of 5% D. All of the above Which step does the cell lyaste become very cloudy and full of a white precipitate? A. The additon of P1 buffer OB. The additon of P2 buffer OC. The additon of N3 buffer D. The additon of PE buffer