FIG 4.

Effects of p53 expression on Tip110 protein and transcription under hypoxia. (A) Saos-2 cells were transfected with the indicated amounts of p53, cultured at 21 or 1% O₂ for 24 h, and harvested for Tip110 and p53 protein expression by Western blotting. cDNA3 was used to equalize the total amount of DNA among all transfections. β-Actin was included as a loading control. (B) Saos-2 cells were transfected with 250 ng pGL3-Tip110 Prom-Luc alone or in combination with 0.5, 1, and 2 μg p53 for 24 h and cultured under 21 or 1% O₂ for 24 h. Cells were harvested for the luciferase reporter gene assay. cDNA3 was used to equalize the total amount of DNA among all transfections. pTK-βgal was included to normalize the transfection efficiency variations among all transfections. The data are means ± standard errors (SE) of triplicate samples and representative of three independent experiments. ***, strongly significant (P < 0.001); NS, not significant.