Lysosomal membrane permeabilization (LMP) and cathepsin activity is involved in thymoquinone-induced cell death.

A) Cytoplasmic vacuolization was observed in U87MG cells after treatment for 1 hour with either TQ or chloroquine, but not in Gli36ΔEGFR cells. At 6 hours, vacuolization can be seen in both cell types. B) Treatment with TQ or chloroquine for 6 hours induces lysosome membrane permeability in U87MG and Gli36ΔEGFR cells, seen as the loss of red acridine orange staining. C) Cells were pre-treated with cathepsin inhibitor III, which primarily targets cathepsin B, for 1 hour. TQ was added and incubated with the cells for 24 hours. Cell viability was measured using the MTT assay.