Immunohistochemistry assays showed that the levels of Ki67, a marker of proliferating cells, and MTCO2, a subunit of the cytochrome C oxidase encoded by the mitochondria, were reduced, and the proportion of cleaved caspase‐3 positive cells was significantly increased in xenograft tumours upon pentamidine treatment (Figure 7F‐H). The gene discussed is MT-CO2; the disease is neoplasm.