Figure 6  .

Overexpression of retinoic acid receptor (RAR)α or γ does not restore retinoid sensitivity in LoVo cells. After stable transfection with the RARα and γ cDNA, overexpression of the respective RAR subtype mRNA was confirmed by northern blotting (A). Transfected (pCMV:RARα7, pCMV:RARα9, pCMV:RARγ23), mock transfected (pCMV), and wild type (WT) LoVo cells were then analysed by human tumour clonogenic assay using the indicated concentrations of all-trans-retinoic acid. (B) After 10 days the number of colonies was evaluated and expressed as a percentage of vehicle treated contols. Results shown are mean (SEM) from three independent experiments, each performed in triplicate.