FIG. 1.

Transactivation by p300 and CBP is stimulated by p21. (A) Schematic diagrams of Gal4 p300 and Gal4 CBP showing the locations of the three cysteine- and histidine-rich domains (C/H), the bromodomain (Bromo), and the HAT domain. (B) Induction of Gal4 p300 and Gal4 CBP activity in U2OS cells. U2OS cells were transfected with 5 μg of the Gal4 E1B CAT reporter plasmid and expression plasmids encoding either Gal4 alone (100 ng), Gal4 Sp1 (5 ng), Gal4 p300 (full length) (100 ng) or Gal4 CBP (full length) (100 ng) as indicated. Four micrograms of Rous sarcoma virus (RSV) p21 or an RSV control (−p21) was included as indicated. Results are the means of at least three separate experiments (with standard deviations).