Trichostatin A (TSA) treatment generates chromosome instability primarily in HCT116 cells. Chromosome counting was performed after cells were treated with 1 μM TSA for 24 and 48 h. (A) The percentage of aneuploidy was greater than 26% after the 24 and 48 h TSA treatments in WI-38 cells, and the effect of TSA was more pronounced in HCT116 cells after 24 h (at 47%) but decreased to 21% after 48 h of exposure. (B-C) The representation of the number of chromosomes from the controls and the 24- and 48-h TSA-treated WI-38 (B) and HCT116 cells (C), showing gains and losses after counting; the black line designates the 2n cells, and the dotted line designates the 4n cells. The total number of chromosomes in 50 cells was counted. The Kruskal-Wallis test yielded p < 0.05 compared with the values of the control (CTR).