Figure 1. p53-dependent repression of Survivin (BIRC5), CDC25C, and PLK1 requires p21.

Log₂ fold-change of mRNA expression in HCT116 A. wild-type and B. p21^−/− cells treated with doxorubicin, Nutlin-3a, or 5-FU for 24 h normalized to untreated cells. Cells treated with DMSO served as a control. GAPDH and U6 served as negative controls, while CDKN1A and MDM2 were assessed as positive controls. Expression levels were evaluated by comparison to GAPDH expression levels using the unpaired Student's t-test. Experiments were performed with two biological replicates and three technical replicates each (n = 6). *p ≤ 0.05; **p ≤ 0.01; ***p ≤ 0.001. C. Flow cytometry of propidium iodide-stained cells used in A. and B.