FIG. 3.

HMGBs enhance RB-mediated transcription repression. (A) HMGBs enhance RB-mediated E2F transcription repression. (B) HMGBs enhance RB-mediated cyclin A transcription repression. RB-negative MDA-MB-468 cells were cotransfected with indicated vectors (0.5 μg/well of each vector in 24-well tissue culture dishes) in the serum-free Dulbecco's modified Eagle's medium containing LipofectAMINE 2000 for 24 hours and then assayed for luciferase activities. Total transfected DNA was kept constant by adding a pcDNA3 control vector. A pSV-βGal plasmid was cotransfected as an internal standard for normalization of luciferase values. Luciferase values are means±SEMs from three independent experiments. The statistical significances were analyzed by the two-tail Student's t-test. *p<0.05; **p<0.01.