Figure 6
From: Phenotypic alterations in breast cancer cells overexpressing the nuclear receptor co-activator AIB1
A proposed model of how increased concentrations of AIB1 and CBP in 436.1 cells compete for a factor that is necessary for estrogen-induced transcription. As schematized on the left, transcriptional activation through the estrogen receptor relies on interaction with AIB1, CBP, and an unknown factor X. In MDA-MB-436 cells, none of these components are limiting. The 436.1 cells have limited amounts of factor X and excess quantities of AIB1 and CBP, which compete for binding to factor X. The absence or presence of a ternary complex of AIB1/CBP/X in 436.1 cells affects the EC50 and transactivation, as schematized.