Figure 4. DNA damage repair ability is reduced in terminally differentiated cells. (A) DNA damage was measured by the comet assay in PMA-treated K562 cells. (B) DNA damage was measured by the comet assay in PMA-treated HL-60 cells. Representative blots are shown. The comet tail moment was counted, and 50 cells were analyzed in each group. ***: p<0.001, compared to control with the Student's t test. Error bars, S.D.