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. 2014 Aug 8;9(8):e104444. doi: 10.1371/journal.pone.0104444

Figure 3. MDM2-ALT1 over-expression leads to G1 phase cell cycle arrest in a p53-dependent and p21-dependent manner.

Figure 3

A. HCT116 wild-type (wt), B. HCT116 p53 −/− and C. HCT116 p21 −/− cells were transfected with myc-tagged GFP or MDM2-ALT1 (2Alt1) or MDMX-ALT2 (XAlt2), harvested 24 hours post-transfection and stained with propidium iodide solution and sorted for DNA content. The bar graphs represent the percentage of cells in the various phases of the cell cycle. Error bars represent the standard error mean from at least 3 independent experiments. HCT116 cells that are wildtype (A) show significantly higher percentage of cells in G1-phase upon MDM2-ALT1 expression (31.44% ±2.45 SEM) compared to GFP-expressing cells (24.40% ±1.40 SEM; n = 5, p = 0.0369). In case of MDMX-ALT2 over-expression in HCT116 wildtype cells, there is no significant change in percentage of cells in G1 phase compared to negative control GFP-expressing cells (p =  0.4389). HCT116 cells that are null for p53 (B) or p21 (C) do not show any differences in the percentage of cells in any of the cell cycle phases upon over-expression of GFP or MDM2-ALT1 or MDMX-ALT2. D. Representative immuno blot showing expression of p53, p21 and loading control GAPDH in HCT116 wt, p53 −/− and p21 −/− cells.