CCL2 and acute kidney injury: Statistical comparison of the protein expression levels of the four experimental groups (Figure 6a) indicated that the expression of KIM-1 (Figure 6b, P < 0.01), TNF-α (Figure 6c, P < 0.001) and MCP-1 (Figure 6d, P < 0.001) in the Normal+HR group was significantly higher, thus suggesting that the in vitro AKI model was successfully established.