Furthermore, transmission electron microscopy revealed increases of dysfunctional, “spaghetti‐like” appearance of mitochondria in stem‐like tumor spheres formed by HCC‐LM3 cells overexpressing YY2 (Figure 4E; Figure S7A, Supporting Information), and more fragmented, less tubular mitochondria in those formed by HCC‐LM3YY2KO cells (Figure S7B, Supporting Information), indicating that YY2 increased dysfunctional mitochondria. The gene discussed is YY2; the disease is hepatocellular carcinoma.