Ectopic expression of p300 in HIPK2 knockdown rescues the p53 apoptotic gene transcription. (a) MCF7indsi/HIPK2 cells, untreated or treated with Dox for HIPK2 depletion and reconstitution (see Figure 2) were treated with ADR (2 μg/ml) and zinc (150 μM) for 16 h. Gene expression of p53 targets was analysed by semiquantitative RT-PCR. GAPDH was used as a control for efficiency of RNA extraction and transcription. (b) RKO cells stable depleted of HIPK2 function were transfected with p300 and treated with ADR and zinc for 16 h. Gene expression of p53 targets was analysed by semiquantitative RT-PCR. GAPDH was used as control. (c) RKO cell depleted of HIPK2 function by siRNA were transfected with p300 or with empty vector by using LipofectaminePlus. After transfection cells were trypsinized and replated and 24 h after transfection treated with ADR. Apoptosis was measured by TUNEL assay 24 h after ADR treatment and shown as percentage of TUNEL positive cells. The results shown are representative of two independent experiments performed in duplicate, ± S.D.