Methanolic extracts of G. tenuistipitata (MEGT) induced DNA double strand breaks of Ca9-22 oral cancer cells. (A) Cells treated with different concentrations (0 to 1 mg/ml) of MEGT for 24 h were stained with γH2AX. (B) Quantification analysis of γH2AX intensity. Data are presented as mean ± S.E. (n = 3). Differences between treatments of different concentrations containing the same letter are not significant.