In a 2D electrophoresis experiment, two proteins with identical isoelectric points are separated. What allows for this separation?

• A. The proteins are separated based on their hydrophobicity.
• B. The isoelectric focusing step separates them based on their different charges.
• C. The proteins are separated based on their tertiary structure.
• D. The SDS PAGE step separates them based on their different molecular weights.

Answer: (D)