Figure 2.

Effects of the combination of Ni and Cuions induced oxidative damage in U937 cells after incubation at 37°C for 24 hours. For statistical significance denoted by dots or asterisks, see legend to Figure 1. The x-axis labels for Figure 2 are defined as follows: Ni²⁺ + Cu²⁺ at 0 means control samples were not treated with Ni²⁺ and Cu²⁺ ions; Ni²⁺ + Cu²⁺ at 5, 10, and 20 means samples were treated with Ni²⁺ + Cu²⁺ ions at 5,10, and 20 µM, respectively.