Figure 2.

The crucial proceed is shown in Figure 2 including MAS, lactate shuttle, and TCA cycle. MDH participates in both MAS and TCA cycle, and catalyzes reversible reaction of NAD⁺ and NADH in cytoplasm and mitochondria, which is also necessary for MDH, LDH, and PDH, key enzymes of the three proceeds. And also, it is like a bridge to facilitate the interaction between energy metabolism of one cell. (A color version of this figure is available in the online journal.)