Copy number analysis of mtDNA in laryngeal cancer. (A) Copy number of mtDNA corresponding to each individual case of laryngeal cancers and normal laryngeal tissues (circle). Real-time quantitative PCR assay was performed to analyze mtDNA copy number in a cohort of laryngeal cancers and normal laryngeal tissues. Details are as described in Methods. (B) Copy number of mtDNA in 30 pairs of laryngeal cancer tissues and their corresponding normal tissues by real-time quantitative PCR. Horizonal lines represent mean ± S.E. N, normal laryngeal tissues; T, laryngeal cancer tissues.