FIG. 2.

MMTV sag-reporter activity in cell lines representing pro-B, pre-B, and mature stages of B-cell development. MMTV sag-reporter proviruses M^sag17-luc (sag17-luc) and M^sag1-luc (sag1-luc), and positive control plasmid CMV-luc were transfected into the pro-B-cell line Ba/F3, the pre-B-cell lines 300-18 and 2M3/M, the B-lymphoma lines A20, CH28, and M12, and the B-cell hybridoma LBB.11. We used 2 pmol of each test plasmid, except for CMV-luc, for which we used 0.5 pmol of plasmid. The full-length MMTV reporter constructs are denoted by plus signs, whereas the negative control constructs lacking the 5′ LTR and most of the internal region are represented by minus signs. Cells were harvested after 24 h and lysed. The relative luciferase activity (RLU) and protein concentration were determined with this extract. The numbers represent the arithmetic mean ± standard deviation (SD) of at least three separate experiments with two different DNA preparations.