Regulation of FeLV replication in response to exogenous overexpression of CBP. K-562 cells were chronically infected with recombinant FeLV containing the LTR of FeLV-945 or FeLV-A/61E. A CBP expression plasmid was then introduced by lipid-mediated transfection. Culture supernatants were collected 3 days later and reverse transcription activity was quantified as a measure of virus production. Results are reported as cpm/ml of 3H-TTP incorporated. The data shown were pooled from two independent experiments each performed in triplicate.