Single Cell Gel Electrophoresis. SYBR-Green stained A. comet showing apparently no damage depicted by the round head and B. comet with tail depicted by arrows indicating presence of damage. C. Tail moments immediately following 2-hour H2O2 treatment and 22-hour recovery in fresh medium. H2O2 concentrations of 60 μM and above resulted in significantly increased tail moments at 2 hours (p < 0.001) which decreased significantly following recovery (p < 0.05) in all lymphoblastoid cells. While there was no significant difference in moments between untreated Normal-L and XP-deficient lymphoblastoid cells (p > 0.05), XP-deficient lymphoblastoid cells exhibited increased tail moments when compared to Normal-L at 2 hours of H2O2 exposure. Following recovery, however, only XPD-L showed significantly higher moments than Normal-L (p < 0.001), while XPB-L showed significantly lower moments. *p < 0.05, **p < 0.01 and ***p < 0.001 indicate significantly greater tail moments when comparing XP-deficient lymphoblastoid cells to Normal-L counterparts. Data is represented as mean ± SE.