English: Figure 2. Optical microscopy images of A549 cells seeded in 12-well plates after 48 h treatment with different concentrations of ZnCl2. Control cells formed a complete monolayer; cells treated with 10 µg/mL of ZnCl2 are still covering the entire surface, but, in higher ZnCl2 concentrations, the majority of cells were detached. (a) Untreated A549 cells and (b–d) cells treated with 10, 40, and 320 µg/mL of ZnCl2, respectively.