Figure 2.

RB represses less efficiently in C33A hbrm-negative cell line. C33A (Left) and SAOS2 cells (Right) were transfected with 1 μg of G1E1B-CAT, 2 μg of GAL4-E2F1, and with 25 and 50 ng (C33A) or 50 and 250 ng (SAOS2) of CMV-RB as indicated. Following a CAT assay, results were quantified using a PhosphorImager. The activity of the reporter in the absence of RB is normalized for both cell lines to a value of 1 (Upper). The level of expressed RB protein was assayed by immunoprecipitation followed by Western blot analysis using XZ55 antibody (Lower). Result of typical experiments is shown.