Figure 3. ARNT and TRIP230 are essential for Rb-regulation of HIF1.

(A) MCF7 cells were transfected with either scrambled siRNA (SCX) or Rb siRNAs siRb 1, and siRb 2, or a combination of TRIP230 siRNA and siRb1. Twenty-four hours after transfection cells were either maintained under normoxic conditions or 1% O₂ for a further 24 h. Gene expression was determined by quantitative real-time PCR after isolation and reverse transcription of total RNA. CXCR4 expression was normalized to constitutively active 36B4 gene expression. (B) Immuno-blot analysis of TRIP230 and Rb after siRNA transfection with either scrambled siRNA, or a combination of siTRIP230 and siRb. Alpha-tubulin (α-tubulin) was used as a loading control. (C) MCF7 cells were transfected with either scrambled siRNA (SCX) or Rb siRNAs siRb 1, and siRb 2, or ARNT, or DP1 siRNA or a combination of ARNT/Rb1 siRNA and treated as described above. (D) Immuno-blot of ARNT and α-TUB after transfection with either scrambled control of siRNA directed to ARNT. (E) Immuno-blot of DP1, TRIP230 and α-tubulin (α-tubulin). MCF7 cells were transfected with either scrambled control (SCX) or siRNA directed to DP1. Data in figure 3A and 3C were analyzed using a two-way-ANOVA. *p<0.01.