Since external melanoma cells constituted the major source of proliferating cells in untreated tri-cultures, their selective loss upon docetaxel treatment reduced the fraction of Ki67-positive cells in the entire tri-culture from 20.9% ± 3.4% (mean ± SEM, n = 5 independent experiments, Fig. 3c) to 10.2% ± 3.0% (mean ± SEM, n = 5 independent experiments, Fig. 3c) after 48 h of treatment. The gene discussed is MKI67; the disease is melanoma.