Tiam1 gene silencing suppresses cell proliferation in vitro. (A) The in vitro proliferative abilities of WT cells, Mock cells, Tiam1KD/clone 2, Tiam1KD/clone 6, and Tiam1KD/clone 8 cells were evaluated by MTT assay. Each value represents the mean ± SD of the absorbance value (OD). Results showed that all Tiam1 knockdown cells grew significantly more slowly than WT and Mock cells, and Tiam1 protein expression correlated with cell proliferation. (B) The plate colony formation efficiency of WT cells, Mock cells, Tiam1KD/clone 2, Tiam1KD/clone 6, and Tiam1KD/clone 8 cells. Data represent the mean ± SD of triplicate dishes. Compared with WT and Mock cells, Tiam1KD/clone 2 had significantly reduced ability for colony formation (P < .01), and Tiam1KD/clone 8 also showed decreased clonogenicity (P < .05). Tiam1KD/clone 6, compared with WT and Mock cells, displayed no difference in clonogenicity (P > .05). Results showed that plate colony formation efficiency also correlated with Tiam1 protein expression.