RPMI 1640 medium contains biotin, vitamin B12, and PABA, which are not found in eagle's Minimal Essential Medium or Dulbecco's Modified eagle Medium. In addition, the vitamins inositol and choline are present in very high concentrations. RPMI 1640 medium with GlutaMAX™ supplement minimizes toxic ammonia build-up and improves cell viability and growth in an easy-to-use format. RPMI 1640 medium contains no proteins, lipids, or growth factors. Therefore, RPMI 1640 medium requires supplementation, commonly with 10% Fetal Bovine Serum (FBS). RPMI 1640 medium uses a sodium bicarbonate buffer system (2.0 g/L) and therefore requires a 5–10% CO2 environment to maintain physiological pH.