**5.5 TRIP-BR1**

The Transcriptional Regulator Interacting with the PHD zinc finger and/or the Bromodomain-1 (TRIP-Br1) protein (also known as p34) is a transcriptional modulator that directly interacts with DP-1, as well as with the co-activators p300/CBP and KRIP1(Hsu et al., 2001). As such, TRIP-Br co-activates E2F responsive genes, such as B-myb, in U2OS osteosarcoma cells, an ability potentiated by KRIP1. This effect is impaired by pRb. TRIP-Br1 also interferes with deactivation of Cyclin D/Cdk4 complex by p16INK4, effectively activating E2F by inhibiting pRb (Sim et al., 2004).
