Subsequently, at the 6 h of cerebral ischemia, the brain levels of protein Kla were significantly increased in the L-lactate and D-lactate preconditioning groups compared to the vehicle group (Figure 6A), as well as the brain lactate levels (Figure 6B); while, protein Kla levels were not markedly changed in mice without experiencing cerebral ischemia (Figure S9A), suggesting that the accumulated lactate would drive the protein Kla formation mainly at the condition of cerebral ischemia insult. Here, KL is linked to brain ischemia.