DNA damage as measured by the comet assay in different cell types. Comet assay was used to assess the extent of DNA damage in terms of tail moment (fraction of DNA in the tail). mTERC+/+ and mTERC-/- MEFs were treated with arsenite [Untreated (Black columns), 1.5 μg/ml (11.5 μM) (dotted columns) and 3.0 μg/ml (23 μM) (white columns)] in the presence or absence of 3-AB. PARP inhibition in mTERC-/- MEFs led to greater increase in DNA damage as compared to wild type MEFs. Data is represented as mean ± SE from three independent experiments. *p < 0.05 when treated cells are compared to respective untreated controls. #p < 0.05 when 3-AB treated cells are compared to respective 3-AB untreated cells in the presence or absence of arsenite. +p < 0.05 when 3-AB treated mTERC-/- cells are compared to 3-AB treated mTERC+/+ in the absence or presence of arsenite treatment.