mtDNA degradation in connective tissue cells. 4B6 or 92TAg cells were exposed to the indicated concentrations of H2O2 for 30 min in HBSS as described in “Methods”, and mtDNA degradation and recovery were assessed by QSBN. Mito, mtDNA band; 18S, 18S (nDNA) band. A, C, and E, representative gel images; B, D, and F, quantitation of band intensities. G, H, I and J, time course of mtDNA recovery in 92TAg cells after exposure to 100 μM H2O2 for 30 min.